******************* Percent Command Set %An Create and configure security accounts. See Appendix D. %Bn Remotely configure the Courier's serial port rate. See Appendix D. %B0 110 bps %B6 9600 bps %B1 300 bps %B7 19,200 bps %B2 600 bps %B8 38,400 bps %B3 1200 bps %B9 57,600 bps %B4 2400 bps %B10 115,200 bps %B5 4800 bps %Cn Remote configuration control. See Appendix D. %C0 Defer configuration. This is the default. Configuration changes are deferred until the call is ended; they take effect for ensuing connections. You do not need to enter this command; it is the default unless you enter %C1 or %C2. %C1 Restore configuration. Use this command to cancel any configuration changes made during remote access, and restore the original configuration. However, commands that have been written to NVRAM (with &W) will not be restored to their previous settings. Additionally, if you have forced immediate configuration changes (with %C2), those changes cannot be reversed with %C1. %C2 Execute configuration. Use this command to force configuration changes to take effect immediately, during the current connection. We recommend against forcing immediate configuration changes unless absolutely necessary, as this can result in an unreliable connection or even a loss of connection. %E=n Make security system edits. See Appendix D. %E=1 Erase local access password. %E=2 Erase autopass password. %E=3 Erase passwords in accounts 0–9. %E=4 Erase phone numbers in accounts 0-9. %E=5 Disable Account, Dialback, and New Number fields in accounts 0-9 disabled. %Fn Remotely configure data format. See Appendix D. %F0 No parity, 8 data bits. %F1 Mark parity, 7 data bits. %F2 Odd parity, 7 data bits. %F3 Even parity, 7 data bits. %L= Assign an account password as the local access password. See Appendix D. %N Works in conjunction with &Xn in synchronous mode. If the modem is set so that it is the source of the Transmit clock timing signals (&X0--default), the %Nn commands set the computer or terminal-to-modem V.25 bis clock speed. If the modem is set to &X1, the computer is the source of the Transmit clock signals. If %Nn is set to 0 or 1, you will receive an error message, since they are not valid values. The %Nn rates are as follows: %N0 Reserved %N6 9600 bps (default) %N1 Reserved %N7 12.K bps %N2 1200 bps %N8 14.4K bps %N3 2400 bps %N9 16.8K bps %N4 4800 bps %N10 19.2K bps %N5 7200 bps %Pn= Disables password security (n=0 or 1) when no character follows the equal sign. See Appendix D. %Pn=s Specify the following password string (s) for viewing privileges only (n = 0) or view and configuration privileges (n= 1). See Appendix D. %Pn? Display password n. See Appendix D. %S=n Obtain access to security accounts without disabling security. See Appendix D. %T Enables the modem, when off hook, to detect the tone frequencies of dialing modems. %T is meant primarily for use with network applications, but may also be integrated into certain software programs. For example, %T could be used in a security program to identify incoming tone security codes. To enable %T, type ATH1 to force the modem off hook. Then type AT%T . To return the modem to Command mode, press any key or drop the computer's or terminal's DTR signal. The modem responds OK. %V=PWn Assign the password in account n in your Courier modem’s security as your autopass password. See Appendix D. Appendix D--Dial Security and Remote Access Operations _____________________________________________________________________ DIAL SECURITY OPERATIONS Dial Security is designed to protect networks and data centers from unauthorized access. The kind of security provided by the Courier modem is different from other kinds of dial security where software is used by the computer to control user access. The Courier’s Dial Security is set up in the modem’s firmware, so access is controlled from modem to modem. Setting up this kind of security requires action at both the host and remote modem sites. This appendix contains instructions for both operations. WARNINGS: If you want to set up Security on your Courier modem, you must complete the steps below in the order listed: 1. Set up your own security account: * Set up your local access password * Enable local access password protection 2. Set up remote user accounts. 3. Enable Dial Security. You must set up your local access security information before enabling Dial Security and allowing remote calls, as outlined under Set Up Your Security Account in what follows. Be sure to remember your local access password; if you enable security and forget your local access password, you risk being locked out of your system. ******** Overview The Courier’s Dial Security allows you to configure up to 10 Security accounts. Each security account is stored in nonvolatile memory (NVRAM) and may be set up in one of three ways: * Automatic password access * Prompted password access * Password with Dialback protection Autopass Autopass is the term we use for the basic implementation of Dial Security in the Courier modem. It is in effect whenever Dial Security is enabled. To use autopass alone, the following requirements must be met: * Both host and remote modems must be U.S. Robotics modems with Dial Security enabled. * The connection must be under V.42 error control (both modems must be set to &M4 or &M5). When the remote modem is set for Dial Security, it automatically includes an autopass password (configured by the remote user to be compatible with the host modem’s security) in its V.42 error control request. The host modem checks all the enabled passwords in its security accounts for a match. If the remote user has set up the modem with an invalid password, the host modem returns an INVALID PASSWORD message and hangs up. If the remote user failed to enable Dial Security on the remote Courier, the host Courier will not accept the call unless prompting (below) is enabled on the host modem. Prompting While the use of autopass (above) is restricted to U.S. Robotics Dial Security modems, prompting allows secured connections with any remote modem whose user has been assigned an allowed password. When prompting is enabled, and the host modem doesn’t receive an autopass password, it prompts the remote user for a password. The host modem checks the received password against each of its active Security accounts. If the password is valid, a secure connection is completed. If the password is invalid, the host modem prompts twice more before disconnecting. If there are no password attempts at the remote end, the host modem times out after 60 seconds and disconnects. NOTE: There is no prompting capability in synchronous mode. Prompting is more flexible than autopass because it: * doesn't require a remote modem to have U.S. Robotics Dial Security. * doesn't require a V.42 connection, so remote modems without V.42 error control capabilities can connect. Optional Dialback Dialback offers an additional layer of security. When the host modem receives a valid password that matches an account and Dialback is enabled, the host first disconnects. The remote user receives a NO CARRIER message. Then the host modem dials back the remote modem. Typically, the Dialback number is stored in the Security account’s phone number field. However, if the security account has been set up to allow a new number, the host prompts the remote user for the new number before hanging up, and then dials back. In order to use dialback, Dial security and prompting must be enabled. **************************************** WHAT THE HOST MODEM OPERATOR NEEDS TO DO Complete the steps below in the order listed: 1. Set up your own Security account. 2. Set up Security accounts for your remote users. 3. Enable Dial Security. 4. Maintain Security accounts. **************************** Set Up Your Security Account Security accounts are set up via an AT command line structure, rather than a screen format. 1. Set up your Security account using one of 10 accounts (numbered 0-9). Each account has five possible fields, as shown in the following table. Password Account Dialback Allow New Dialback Enabled Enabled Enabled Number Number 8 chars. max. YES/NO YES/NO YES/NO Up to 37 ASCII 37-127 characters case sensitive* (0-9) BILL Y Y N 1-419-555-5555 * If "BILL" is the password, "Bill" is an invalid entry. Use the %An= command and format (below) to set up accounts, where n is the account number, 0-9. The fields in the above table are entered after the equal sign, each separated by a comma, as in the following example for account 0 with the password BILL. WARNING: Do not insert spaces between commas or between fields and commas. Spaces will invalidate the command. AT%A0=BILL,Y,Y,N,1-419-555-5555 This example instructs the modem to store the configuration for account 0: password (BILL), account enabled (Y), dialback enabled (Y), allow a new number (N), and the dialback phone number. NOTE: The %An= command is automatically written to NVRAM and does not require an &W. Some accounts may have fewer security options. The following example sets the password (Judy) and enables account 1 without any dialback options. AT%A1=Judy,Y,,, Each security function can be configured or modified independently. If a field is to remain as is, just insert a comma, as shown in the following command. It allows the remote user to supply a new Dialback number different from the one stored in the original account record. AT%A0=,,,Y, 2. Set up your local access password. This password protects the Security accounts from unauthorized users. When this protection is enabled, you cannot view, modify, or tamper with the Security accounts unless you enter the correct local access password. The local access password must be chosen and protection must be enabled before Dial Security is enabled. In the following example, the local access password is the same as the password in account 0. AT%L=PW0 ******************************** Set up Accounts for Remote Users Once your account is configured and password protection has been enabled, you can set up the remote user accounts. Use the %An= command (using the same guidelines you used to set up the system administrator’s account in Step 1 of the previous section) to set up remote user accounts. Once security accounts have been enabled, you are responsible for communicating valid password information to your remote users. ******************** Enable Dial Security Once you have completed the previous steps, you are ready to enable Dial Security. When you enable Dial Security, you must choose either autopass or prompting as the security method. You must know what types of modems remote users are using and set the Dial Security parameters accordingly. Autopass is limited to U.S. Robotics modems with Dial Security, but prompting is not. 1. Register S53 is the bit-mapped register used to enable Dial Security. The &W command must be used to save Register S53 settings to NVRAM. Otherwise, when the computer is powered off and on again, or the modem is reset using ATZ, it will default to S53=0, Dial Security disabled. To enable Dial Security with autopass and local access password protection, but without prompting, type the following command: AT S53.0=1 .2=1 &W The following command enables Dial Security with autopass, prompting, and local access password protection. AT S53.0=1 .1=1 .2=1 &W NOTE: Enabling local access password protection disables the &Zn=s command that stores up to ten phone numbers. Stored phone numbers occupy the same space in NVRAM as the dialback numbers for Dial Security accounts, and cannot be used when Dial Security is enabled. If the local access password is not protected, the &Zn=s command overwrites the corresponding Dial Security dialback number. For example, the following command overwrites the dialback number for account 5: AT &Z5 = 555-8976 However, if the local access password is protected, and a user tries to use the &Zn=s command, an ACCESS DENIED message is displayed. WARNING: Be sure DIP switch 10 is OFF so the modem will load the settings stored in NVRAM. If someone sets DIP switch 10 ON, the low performance template settings (&F0) are loaded, and Dial Security is disabled. If this should happen, reset DIP switch 10 to OFF, power off the modem and power it back on, or reset the modem by typing ATZ so that the proper settings take effect. ************************** Maintain Security Accounts Once the local access password is set and protected, the system administrator is the only one who can access account information. To modify or change account information, use the %S= and %E= commands described next. Account Access (%S) Once Dial Security is enabled, you can access accounts by entering the local access password using the %S= command, which allows access to the accounts by disabling local security. AT%S=(your local access password) NOTE: The modem echoes the local access password, which is case sensitive. The system will accept an invalid password entry, but will lock you out from the modem’s security commands. For example, if the password is Bob, but you enter BOB, an OK is displayed. However, if you try to type a security command (for example, ATI10 to view accounts), an ACCESS DENIED message is displayed. Account Status Once access has been granted, you can view account information by typing the I10 option of the Inquiry (I) command: ATI10 Remote users may only use this command during a remote access session if local access security is disabled. Erasing Account Information (%E) Use the %E=n command to make system edits. %E=1 Erase local access password. %E=2 Erase autopass password. %E=3 Erase passwords in accounts 0-9. %E=4 Erase phone numbers in accounts 0-9. %E=5 Disable Account, Dialback, and New Number fields in accounts 0-9. To edit or overwrite an individual account, or an individual account field, use the %An= command described in Set Up Your Security Account, earlier in this appendix. Remote Configuration Dial Security accounts may be configured remotely. See Configuring Dial Security Remotely at the end of this appendix. ********************************** WHAT THE REMOTE CALLER NEEDS TO DO When remote users want to call in to your Courier (assuming you have enabled Dial Security), they must contact you to obtain a valid password. They must also find out if they must set the remote modem for auto answer (necessary if your modem uses Dialback as a security method). 1. If the host modem security is set up, get a password from the host modem operator. Passwords are case-sensitive, so be sure to copy it down correctly. If the host modem security is set up for prompting and the host operator enables dialback for your account, skip to Step 3. 2. For remote users with COURIER modems only. Set up security on your modem, including an account that uses the password the host asked you to use. Refer to Set up Your Security Account, earlier in this appendix, for instructions. Then assign the password as your autopass password. Enter the following command, where n is the number of the account you set up): AT %V=PWn You can check to see that you've correctly set up your autopass password by typing the following command: AT I10 Your autopass password appears in the right-hand column below FORCED AUTOPASS. Once the autopass password is set, enable your Courier modem’s Dial Security with the following command: ATS53.0=1 &W 3. If Dialback is enabled at the host Courier site, set your modem to answer the host modem when it disconnects and dials back. To set the modem to answer the Dialback call, set DIP switch 5 OFF and reset the modem (ATZ ). Alternatively, type the following command: AT S0=1 4. Call the host modem. 5. When the call is completed, if you want to disable auto answer, do one of the following: * Set DIP switch 5 ON and reset the modem (ATZ). * Type the following command: AT S0=0 ___________________________________________________________________________ REMOTE ACCESS OPERATIONS You can set a Courier modem so that someone at a remote location can configure your modem. This might be helpful if you have problems making a connection with another modem. For example, if you have trouble connecting with a bulletin board, you can allow the bulletin board operator to dial in to your modem and view its configuration settings. If necessary, the bulletin board operator can send the Courier a configuration string that will make it compatible with the bulletin board. Another use might be for Dial Security administration when the system administrator is unable to be at the host modem site. It might be urgent, for example, to disable an account. ************************* AT THE HOST COUTRIER SITE There are two tasks required to set up remote access: 1. Set up password security. 2. Enable remote access. ************************ Set Up Password Security You can designate two passwords for remote access security, each allowing a different level of access to the remote user. You can assign one password that allows viewing privileges only, whereby the host Courier's configuration can be remotely viewed but not changed. You can assign another password that allows both remote viewing and configuration privileges. Remote access passwords can be up to eight alphanumeric characters long, and are not case-sensitive. %Pn Use the %Pn command to assign remote privileges. %P0 Viewing privileges only %P1 Viewing and configuration privileges To assign a password that allows viewing privileges only, use the command format below: AT%P0=[password] To assign a password that allows viewing and configuration privileges, use the command format below: AT%P1=[password] Disabling Password Security If you want to disable an assigned password (and thereby disable remote access security), use the following command format: AT%P0= or AT%P1= WARNING: If you disable the %P1 password, a remote user does not need to enter a password for configuration access. ******************** Enable Remote Access Set Register S41 for a value of 1 or greater. S41 is used to set the number of allowable login attempts, as explained later. A setting of zero allows no login attempts, and thus disables remote access. AT S41=1 NOTE: This method will not work if your modem is attached to certain synchronous devices. Refer to Appendix F for more information. LED Indicator for Remote Access The Courier's SYN status light indicator (LED) flashes to indicate when it is in a remote access session. ************************ AT THE REMOTE MODEM SITE Remote configuration can be performed at any time during an asynchronous connection. The user performing remote configuration can use any modem; it does not have to be a U.S. Robotics model. 1. Make sure the host Courier has been set for remote configuration, as described earlier. Then establish a connection. It does not matter which modem originates the call. 2. After a connection has been established, send the following escape sequence: Pause four seconds, type four tildes: ~~~~ and pause another four seconds. NOTE: You can change the escape sequence character with Register S42. The pause duration (guard time) can be modified with Register S43. (These values are set at the host Courier modem.) 3. When the Courier begins its login sequence, the caller will see a display similar to the following: U.S Robotics Courier HST Dual Standard V.34 Fax Remote Session Serial Number 000000A000000001 4. At this point, if password security is active, the caller is prompted for the password. Password (Ctrl-C to cancel)?..... As described earlier in Password Security, entering the password assigned by the %P0 command allows viewing privileges only. Entering the password assigned by the %P1 command allows viewing and configuration privileges. Note that there is a 3-minute time limit for entering the password. As mentioned earlier, if the number of unsuccessful login attempts exceeds the set limit, the modem returns online and refuses any further login attempts during the remainder of that connection. When a password is accepted, the Courier indicates that it has entered Remote Access mode and the remote prompt appears on the remote caller's screen. Access Granted Remote-> 5. If password security is not active (no passwords have been set or both passwords are disabled), the Courier automatically enters Remote Access mode and the remote prompt appears on the remote caller's screen. Remote-> 6. Once the remote access session has been established, keep in mind that there is a 3 minute inactivity timer. If the modem detects no activity for 3 minutes, it aborts the remote access session and resumes a normal online connection. Aborting the Request for Remote Access If you want to abort the remote access login before you have entered the password, return online by pressing -C or typing ATO . ******************************** Remote Viewing and Configuration Once you've gained remote access, you can communicate with the host Courier as if you are entering commands at its attached computer. Depending on your access privileges, you can use the regular Courier AT commands. If you have view privileges only (with %P0), you can use any of the view (Inquiry) commands described in Chapter 6. If you have view and configure privileges (set with %P1), you can use any of the modem commands, except those commands that cannot be used while online, such as the Dial command. You can also use the remote configuration commands explained later. When you make remote configuration changes, the remote prompt is altered to indicate that changes have been made. The prompt will change from: Remote-> to Remote+> If you restore the original configuration (with %C1, explained next), the original prompt is also restored (back to Remote->), indicating that the original configuration is intact. By default, configuration changes do not take effect until the connection is terminated (see %Cn). However, the new configuration is immediately reflected on the information screens (ATIn). ***************************** Remote Configuration Commands There are some additional commands that are only executable during a remote access session. These commands are as follows. %Bn Configure the Courier's serial port rate. %B0 110 bps %B6 9600 bps %B1 300 bps %B7 19,200 bps %B2 600 bps %B8 38,400 bps %B3 1200 bps %B9 57,600 bps %B4 2400 bps %B10 115,200 bps %B5 4800 bps %Cn Configuration control. %C0 Defer configuration. This is the default. Configuration changes are deferred until the call is ended; they take effect for ensuing connections. You do not need to enter this command; it is the default unless you enter %C1 or %C2. %C1 Restore configuration. Use this command to cancel any configuration changes made during remote access, and restore the original configuration. However, commands that have been written to NVRAM (with &W) will not be restored to their previous settings. Additionally, if you have forced immediate configuration changes (with %C2), those changes cannot be reversed with %C1. %C2 Execute configuration. Use this command to force configuration changes to take effect immediately, during the current connection. We recommend against forcing immediate configuration changes unless absolutely necessary, as this can result in an unreliable connection or even a loss of connection. %Fn Configure data format. %F0 No parity, 8 data bits. %F1 Mark parity, 7 data bits. %F2 Odd parity, 7 data bits. %F3 Even parity, 7 data bits. Password Commands %Pn= Disables password security (n=0 or 1) when no character follows the equal sign. %Pn=s Specify the following password string (s) for viewing privileges only (n = 0) or view and configuration privileges (n= 1). %Pn? Display password n. Command Format When typing commands during the remote access session, no delay between command strings is necessary. For example, you can type the following commands without pausing after each one: * a password: ABCDEF * a configuration string: AT&H1&R2&W * and a request for an information screen: ATI5 The maximum number of characters between carriage returns is 40. Ending a Remote Access Session One of four commands ends a remote access session. * -C aborts the login procedure. * ATZ resets the modem and terminates the connection. * ATH terminates the connection. * ATO or ends the remote access session, but the modems remain online. ********************************** Configuring Dial Security Remotely The system administrator can configure host Courier security account information with a Courier modem at a remote site using the procedures described below. NOTE: Before remote configuration is possible, the local modem's remote access must be enabled, and a remote access password that allows viewing and configuration privileges must be assigned. For convenience, you may want to use your local access password as your remote access password. Dialing In From the Remote Site 1. From the remote site, connect to the host modem using Dial Security. Once a connection is made, follow the instructions for beginning a remote access session as described earlier in this appendix. 2. When remote access has been granted, use the %S= command to access the Dial Security accounts. 3. If you wish, you can view account information by typing the following Inquiry (I) command: AT I10 4. Make any configuration changes and execute them immediately by typing the following command: AT %C2 5. To end the remote session and reactivate local access security on the host modem, reset the modem by typing: ATZ WARNING: If you do not use the ATZ command to end a remote access session, local access security will remain disabled at the host Courier site and anyone dialing in to your modem for remote access will have access to the I10 screen and all Security accounts. Appendix E--Troubleshooting You may occasionally encounter one of the problems listed here. They are divided into three categories: Running the SDL.EXE Upgrade Program, Before Establishing the Link, and During Data Transfer. *********************************** Running the SDL.EXE Upgrade Program Your modem . . . Is indicating an error Try running the SDL program at a lower serial port rate. If your computer doesn’t have a 16550 UART, a slower serial port rate can make all the difference. You can also try running the program on a different PC. An idiosyncracy of an off-brand PC or an uncommon version of DOS may lock up the SDL program. *************************** Before Establishing the Link Your modem . . . Doesn't answer the phone or go off hook to dial a number Review your communications software manual to see what Data Terminal Ready (DTR) operations your software requires. Then check to see if DIP switch 1 is set correctly. Also, check to make sure your terminal or computer is sending a DTR signal via the RS-232 interface. Doesn't respond OK when you type AT 1. Make sure you're typing in either upper case or lower case letters, not a combination, and that you press the Enter key. 2. If you're using a computer, make sure it is in Terminal mode. This is a communications software function. See Testing the Modem in Chapter 2. 3. Check to see that your terminal or software is set to the correct bit rate and word length (7 bits with or without a parity bit, or 8 bits and no parity). If you're using a computer, make sure your software is set to the correct communications port. 4. Check that DIP switch 8 is ON, for command set recognition. If the switch is OFF, power off the modem, set the switch ON, and power on the modem again. Try typing AT again. 5. Check that DIP switch 3 is ON, for result code display, and that DIP switch 2 is OFF, for verbal result codes. If not, change the switch(es) and type ATZ . Or type whichever of these commands is needed: ATQ0 (to enable the message) ATV1 (to display a verbal message) 6. Review your communications software manual to see what Carrier Detect (CD) operations your software requires. Then check to see if DIP switch 6 is set correctly. 7. A rare condition is that your terminal or computer reverses the send/receive functions at the RS-232 interface. See your equipment documentation. Displays double characters Both your modem's and software's local echo are on. You can turn your software's local echo off. Or turn the modem's echo off by either resetting DIP switch 4 and sending the modem the ATZ command, or by sending the modem the ATE0 command. Your computer . . . Reacts as though a data link has been established, but no call has been received DIP switch 6 is set ON at the factory for Carrier Detect (CD) override, but your system may require that the override be turned OFF. Review your terminal's manual or your communications software manual to see what CD operations are required. Then check to see if DIP switch 6 is set correctly. When the modem is in Answer mode, it acts as though a Carriage Return has been entered, but nothing has been typed at the keyboard Your software may be misreading signals from the modem as it automatically sends a Carriage Return and a Line Feed before and after the RING and CONNECT messages. Sending the Quiet mode command, ATQ1 , should solve the problem. Both modems . . . Exchange carrier signals, but fail to establish a communications link 1. If you have a fax modem, make sure it is in the correct mode, fax or data, depending on whether the connection is to be made with a facsimile device or a data modem. See Fax Operations in Chapter 5 for information on switching between Fax and Data modes. 2. Asynchronous operations: Check to make sure the proper bit rate, word length, parity and number of Stop bits have been selected. Synchronous operations: review the link instructions in Appendix F. If you've set the modem to the correct configuration, the problem may be with the synchronous adapter or with the system you're trying to call. 3. Check to see that your modem is at the correct Bn setting to connect with either an HST modem (B1 setting) or V.32 terbo modem (B0 setting). Type ATI4 for a display of the Courier's current settings and, if necessary, send the modem the correct setting. 4. If your modem is attempting to answer a V.32 call, you may need to lengthen the extra V.32 answer tones. See S28 in Appendix B. 5. Depending on your model, make sure the modem at the other end of the line is HST compatible, V.32 terbo compatible at 14.4K bps, or V.32 compatible at 9600 bps, V.22 bis-compatible at 2400 bps, Bell 212A-compatible at 1200 bps, or Bell 103-compatible at 300 bps. These are the common signaling standards for full duplex dial-up network transmission in the U.S. 6. Make sure your modem's connection rate setting, &Nn is correct for the call. If the connection rate is locked at a speed (&N1-&N14) different from the calling modem's, the Courier hangs up. The factory setting of &N0, variable link operations, allows the two modems to negotiate the highest possible connection rate. 7. If none of the above corrects the problem, it's likely that the quality of the phone connection is poor and that the other modem is missing the signals your modem is transmitting. The variable quality of phone line connections may be due to any number of conditions in the phone service's equipment or the current environment. Try several calls, and if you still can't get through, try calling another modem. If the second modem accepts your call, the problem may lie with the modem you first tried to call. ******************** During Data Transfer Your screen displays . . . Only brackets Check to make sure that both modems are set to the same bit rate, word length, parity and number of Stop bits. If the settings are correct, the problem may be with the phone line. Try the following measures: 1. Try placing the call again. The phone company routes even local calls differently each time you call. 2. Try calling a different modem to see if the problem persists. The problem may be with the modem you first tried to call. Random or garbage characters Check to make sure that both modems are set to the same bit rate, word length, parity, and number of Stop bits. If the modem is set to a fixed serial port rate (&B1) and your software is fixed at 19.2K, 38.4K, 57.6K, or 115.2K bps, the reason may be one of the following: 1. Your computer may not support the high rate. If this is the case, fix your software rate at 9600 bps and disable high-speed V.32 terbo modulation: ATS34=3 or ATS34 .0=1 .1=1. 2. If you use memory-resident programs (TSRs), they may be interfering. Try disabling them before you run your communications software. The same is true of disk-caching programs. 3. Check to see that your software and the modem are set for the same kind of flow control, either hardware or software. Some communications programs also require that you disable the kind you are not using. Double characters Your modem's online local echo is on and the remote modem is also echoing. The only way to correct this is to bring the modem back to Command mode (wait one second without transmitting data, type +++, wait another second). Then type the command to turn off your online echo (ATF1 ). If DIP switch 9 is OFF (factory setting), the modem hangs up when it returns to Command mode, and you'll have to call again. If DIP switch 9 is ON, the modem maintains its connection. You can return it back online by typing ATO . ************************** IF YOU STILL HAVE PROBLEMS The problems described above are by far the most common ones that users encounter. If the suggestions we've given don't clear up your difficulties, try the following: 1. Review the manual carefully to see if you've missed something. 2. Call or visit your modem dealer. Chances are your dealer will be able to give you the assistance you need. This is much more efficient and time-saving than returning the modem to U.S. Robotics. 3. If your dealer can't help you, refer to the Customer Service Access Card provided in this package. This card lists several important U. S. Robotics numbers. 4. If you must return your modem to us, the Service Representative you talk to will give you a Return Materials Authorization (RMA) number. Modems without an RMA number will not be accepted. 5. If you do return the modem to us, please use the following procedures. a. Ship the unit, postage paid, in its original container. If the original container is not available, pack the modem carefully in a strong box of corrugated cardboard with plenty of packing material. b. Be sure to include your RMA number inside the package, along with your name and address. Put your return address and your RMA number on the shipping label as well. c. Ship the well-packed modem to the following address. Technical Support Department U.S. Robotics, Inc. 8100 North McCormick Boulevard Skokie, Illinois 60076-2999 d. Please note that U.S. Robotics will not accept packages sent COD, so be sure to send the modem postage paid. e. U.S. Robotics will repair your modem and return it to you via United Parcel Service. Appendix F--Synchronous and Dedicated Line Operations ___________________________________________________________________________ SYNCHRONOUS APPLICATIONS Synchronous mode is required for users who need to call, or receive calls, from a Host computer of a large network. The Host is usually a mainframe. There are two ways the Courier can operate in synchronous mode: * Selecting the ITU-T standard V.25 bis protocol, which formats data in HDLC or character-oriented frames. This method is used by mainframe operators and synchronous terminal users. V.25 bis acts as an interface between the mainframe and modem, sending synchronous responses. An asynchronous device or a "dumb" terminal is used to configure the modem before it dials out in synchronous mode. * Dedicating a PC as a synchronous device by installing the proper hardware and software so it can communicate with a mainframe. The modem is configured and dials out in asynchronous mode, then switches to synchronous mode once a connection is made. NOTE: HST modulation is not supported for synchronous communications. ******************** GENERAL REQUIREMENTS Courier modems in asynchronous mode adapt to many conditions of remote asynchronous modems. But synchronous connections to a mainframe require strict adherence to specific operating parameters. If you are operating a terminal designed for a particular network, you probably need only set the Courier properly before calling or answering. NOTE: The term DTE in the following discussion means Data Terminal Equipment, the end-to-end equipment involved in data communications. DTE denotes your terminal or computer and the remote computer. ********************* What You Need to Know The network's communications management staff can supply information on the following requirements: * The protocol needed for your calls * The software support needed to log into the network; for example, a specific communications package or interface board * The phone number, if you will be calling instead of answering * Any restrictions about when you can call ******************** The RS-232 Interface Transmit and Receive synchronous timing pins are required at the RS-232 interface. You'll need either pin 15 or pin 24 for Transmitter timing signals, depending on whether the modem (pin 15) or the DTE (pin 24) generates the signals. You'll also need pin 17, for Receiver timing signals. If you're building your own cable, review the RS-232 Interface, in Appendix B. ********************** Protocol Compatibility The devices at both ends of the link must use the same protocol. These protocols format data into blocks or frames and add control information. If the modem is in V.25 bis mode, the link protocol must be HDLC (High-Level Data Link Control), or character-oriented. If the modem is in Online Synchronous mode it may use HDLC, character-oriented, or another protocol determined by the mainframe manufacturer. ****************************** Data Rate Synchronization (&Xn) During synchronous operations, transmit and receive clocks at both ends of the phone link control the precise timing of the data flow. The communications equipment at the remote DTE and your modem and DTE must all handle the data at the same speed. The transmit clock timing signals setting, &Xn, determines whether the modem or DTE will generate the timing signals. For Online synchronous operations, the source for this setting must be the same on both systems. See Connection Rate (%Nn, &Nn) later in this appendix. Most Online synchronous users will require the default setting, &X0. &X0 The Courier is the source of the Transmit clock timing signals and sends them to your DTE over the RS-232 interface. The DTE rate will follow the connection rates. Default. &X1 The DTE is the source of the Transmit clock timing signals and sends them to the Courier over the RS-232 interface. This setting is used typically in leased line multiplexed operations. (Multiplexors divide the phone channel so that the channel carries several calls at the same time.) The DTE ignores the Courier's clock timing signals and negotiates the DTE and connection rates. &X2 The Courier's Receiver clock is the source of the timing signals. The signals are looped to the Transmit clock and sent to your DTE over the RS-232 interface. This setting is only used in those systems that require synchronization of data flowing in both directions. ********************** V.25 BIS RREQUIREMENTS V.25 bis is an ITU-T standard that uses the HDLC or character-oriented protocols to format data. Before you attempt to connect to a synchronous network, you must configure the modem in command (asynchronous) mode by using either an asynchronous device or dumb terminal. V.25 bis commands are used for this purpose. The computer or terminal sends V.25 bis commands to the modem to ready the line for synchronous transmission. Once the synchronous connection is made and the modem is in synchronous mode, V.25 bis commands are no longer necessary and are ignored. The modems on each end of the connection are transparent to the host computers or terminals. To set the modem, follow the instructions in Chapter 4, Command Set Usage. Commands begin with a required AT prefix and end with a required Carriage Return, which we denote with the symbol . For example, the following command causes the modem to set the connection rates, enable normal result codes, enable auto answer, select HDLC as a link protocol, and save the settings to NVRAM. Spaces have been added only for readability. AT &N0 %N6 X0 S0=1 &M7 &W Be sure that DIP switch 10 is OFF so that the modem loads the settings you've stored in nonvolatile random access memory (NVRAM) when it powers on. Until you customize your own settings, the settings in NVRAM are the same as the &F1 Hardware Flow Control template. ************************** Connection Rate (&Nn, %Nn) There are three phases to obtaining and maintaining a connection rate during synchronous communication. Clock Speed Control The first phase is in deciding where the clock speed will be determined. (See Data Rate Synchronization, above.) Offline Host/Modem Clock Speed The second phase involves the data rate between the host computer or terminal and its modem during offline mode. The %N command is used to set the clock speed between the modem and host, but this speed is only during offline mode, before the synchronous connection is made. The %Nn command works in conjunction with &Xn. If the modem is set so that it is the source of the Transmit clock timing signals (&X0--default), the %Nn commands set the computer or terminal-to-modem V.25 bis clock speed. If the modem is set to &X1, the computer is the source of the Transmit clock signals. If %Nn is set to 0 or 1, you will receive an error message, since they are not valid values. The %Nn rates are as follows: %N0 Reserved %N6 9600 bps (default) %N1 Reserved %N7 12.K bps %N2 1200 bps %N8 14.4K bps %N3 2400 bps %N9 16.8K bps %N4 4800 bps %N10 19.2K bps %N5 7200 bps Online Connection Rate The &N command sets the data rate during the synchronous connection. If &Nn is set for 2-10, the modem ignores the %Nn rate and follows the &Nn rate to set the Online connection rate. The &Nn rates are as follows: &N0 Variable (default) &N6 9600 bps &N1 Reserved &N7 12K bps &N2 1200 bps &N8 14.4K bps &N3 2400 bps &N9 16.8K bps &N4 4800 bps (terbo-terbo only) &N5 7200 bps &N10 19.2K bps (terbo-terbo only) Recommended Settings When the connection is made and the data rate is determined, host/modem rates may change dramatically to match the connection rate (when in online synchronous mode, the modem is transparent on the line). To avoid this dramatic rate switching (which can be hard on some computers), we recommend that the modem be set with a fixed rate between the computer or terminal and modem (%Nn) and that the connection rate (&Nn) be set to the same rate. ***************** Result Codes (Xn) The Courier displays normal or extended synchronous result codes, depending on the setting of the Xn command. By default, the modem is set to X1 for extended result codes. To change to normal result codes, set the modem to X0. The normal result codes return messages such as VAL or INV (VALID or INVALID), whereas the extended codes offer explanations-- INVPS (INVALID Parameter Syntax Error). ************************** Automatic Answering (S0=1) When the Courier is operating in V.25 bis mode, it ignores the DIP switch 5 setting, which controls Auto Answer. To set the modem to automatically answer incoming calls, set the modem to S0=1, so it answers on the first ring. You can substitute a higher value. See the S-Register summary in Appendix B. Suppressing Auto Answer To disable Auto Answer, set the modem to answer on zero rings, S0=0. ************************************* Choosing a Synchronous Protocol (&Mn) Once the &Xn, %Nn, &Nn, Xn, and S0 commands are configured, you must use the &Mn command to choose the HDLC or character-oriented link protocol so that your synchronous software can properly format its commands. &M6 Use the character-oriented protocol for synchronous communications. The Courier and the remote modem must use the same eight-bit data format. The character length must be 7 bits and either ODD or EVEN parity (ODD is preferred), or 8 bits and NO parity. &M7 Use the High Level Data Link Control (HDLC), an ITU-T standard for synchronous communications. HDLC ignores parity. ********************************** V.25 bis Commands and Result Codes Commands * CIC (Connect incoming call) Instructs the modem to answer an incoming call. * CRN (Call request using number provided )Instructs the modem to dial the number following this command. Example: CRN18001234 * CRS (Call Request with memory location)Instructs the modem to dial a number stored in memory. Example: CRS3 * DIC (Disregard incoming call)Instructs the modem to disregard an incoming call--overrides auto answer for this call. * PRNn (Program number) Stores a number in NVRAM. Example: PRN3; 18001234 * RFN (Request list of forbidden numbers)Instructs the modem to list the numbers with which the modem is unable to connect. * RLN (Request list of stored numbers)Instructs the modem to list those numbers previously stored in NVRAM. Dial Options 0-9 Digits & Flash : Wait for dial tone > (Greater Than) separator < Pause = (Equal Sign) separator P Pulse T Tone . (Period) separator - (Minus) separator Result Codes * SFI (Call failure indication) with optional parameters: - CFAB (Abort call) - CFCB (Local modem busy) - CFET (Engaged tone) - CFFC (Forbidden call) - CFNS (Number not stored) - CFNT (Answer tone not detected) * CFRT (Ring tone) * CNX (Connect) * LS (List of numbers) * LSF (List of forbidden numbers) * LSN (List of stored numbers) * INC (Incoming call) * INV (Invalid) with optional parameters: - INVMS (Message syntax error) - INVCU (Command Unknown ) - INVPS (Parameter syntax error ) - INVPV (Parameter value error ) * VAL (Valid) Commands and Result Codes NOT Supported * CRI (Call request with identification number) * PRI (Program identifier) * RLI (Request list of identification numbers) * RLD (List of delayed call numbers) ********** Hanging Up Since the modem cannot accept commands once it is connected in synchronous mode, you cannot use the ATH (hang up) command or the +++ escape sequence. The only way for the modem to disconnect is to drop its DTR signal. This is normally done with software. However, if the modem is initially set to S32=6 when it is in asynchronous mode, the modem will reset when the voice/data switch is pressed, thus dropping DTR. ****************************** Returning to Asynchronous Mode Once you've completed a communication session, you can switch between synchronous and asynchronous modes by flipping DIP switch 10 OFF (factory settings, asynchronous mode) and then ON (NVRAM settings, synchronous mode if the modem is set to &M6 or &M7). The modem cannot switch between synchronous and asynchronous while a call is connected. ******************************* ONLINE SYNCHRONOUS REQUIREMENTS Although personal computers do not usually support synchronous communications, they can be dedicated to do so. If you have a personal computer you must find out what hardware and software you need before setting the Courier for synchronous calls. **************************** The Synchronous Adapter Card You will probably have to purchase and install a synchronous adapter card. These cards are multifunction boards that provide the following functions: * A synchronous port from the DTE to the modem * One or more synchronous protocols. Be sure to find out which protocol the Host mainframe requires before you purchase an adapter. * Additional software functions. For example, you need to identify the type of computer or terminal you are using to the mainframe software. You will most likely also have to specify your application--that is, identify the mainframe resources you want to use. ***************** Setting the Modem When the modem is set to Online Synchronous mode, it remains in command (asynchronous) mode until it makes a synchronous connection with a remote modem. Upon connection, the Courier enters synchronous mode and sends synchronous timing signals to your DTE. Because the modem will not accept commands when it is in synchronous mode, you will have to configure it in asynchronous mode before trying to connect to a synchronous network. NOTE: Be sure that DIP switch 1 is OFF (factory setting). The Data Terminal Ready (DTR) override must be OFF so that the Courier detects when the DTE raises and lowers the DTR signal. To set the modem, follow the instructions for issuing commands in Chapter 4, Command Set Usage. Commands begin with a required AT prefix and end with a required Carriage Return, which we denote with the symbol . For example, the following command causes the modem to set the modulation, the connection rate, and choose a timing source. Spaces have been added only for readability. AT B0 &N0 &X0 ************************************ Modulation/Connection Rate (Bn, &Nn) Use the following guidelines for your Courier type. V.Fast Class does not support synchronous mode. V.32 terbo modems If the modem is connecting with another U.S. Robotics V.32 terbo modem, set both modems to B0 and to a variable connection rate, &N0. The modems will connect at the highest possible rate. If the Courier V.32 terbo is to connect with a V.32 modem, set the Courier to B0 and try a variable connection rate first, &N0. If that doesn't work, try a fixed connection rate of &N6 (9600 bps) or &N3 (2400 bps). Modems in HST mode HST modulation for synchronous communications is not supported. Dual Standard modems Set the Dual Standard modem to B0. Try a variable connection rate setting (&N0) first. If that doesn't work, you may have to set a fixed connection rate, for example, &N6 (9600 bps). NOTE: If your modem is set to a fixed rate, and the remote modem is not set to the same rate, your modem hangs up. ********************* Connection Rate (&Nn) Use this command to set variable or fixed rates at the link interface. The default is &N0, variable rate. The Courier negotiates with the remote modem for the highest possible connection rate, depending on the capabilities of the remote modem. If &N0 does not work, try a fixed rate. NOTE: The modem is not capable of connecting at 21.6K bps in synchronous mode. When you set the modem to a fixed rate, it will only connect if the remote modem is operating at the same rate. If not, your modem hangs up. The fixed rate options are as follows: &N0 Variable rate &N6 9600 bps &N1 Reserved &N7 12K bps &N2 1200 bps &N8 14.4K bps &N3 2400 bps &N9 16.8K bps &N4 4800 bps (terbo-terbo only) &N5 7200 bps &N10 19.2K bps (terbo-terbo only) ******************************* Generating Clock Timing Signals The &Xn setting specifies whether the Courier or your DTE generates the Transmit clock timing signals for a synchronous call. Most users will require the default setting, &X0. See Data Rate Synchronization (&Xn), earlier in this appendix, for more information. *********** Dialing Out The modem's stored command feature (&ZC=s) allows you to configure the modem for a synchronous connection and to dial out to the Host computer by just pressing the voice/data switch. Below are our recommended procedures. 1. If your communications software isn't running, load the program and put the computer in Terminal mode, as described in Chapter 2. Terminal mode allows you to send AT commands directly to the modem. 2. Using the guidelines in Chapter 4, store a command string (&ZC=s) that configures the modem according to the Host computer's requirements. In addition, include the &M1 command, to have the modem enter synchronous mode, followed by the appropriate Dial string. The following is an example: AT &ZC = &F &X1 &M1 DT5551234 In the example, &F sets the modem's defaults as those of the &F0 template settings, while &X1, which specifies the computer as the synchronous timing source, is the only non-default setting used besides synchronous mode (&M1). Any non-default settings should follow the &F command. The Dial command should be the last entry before the Carriage Return. 3. Set the voice/data switch to option 9, so that the modem executes the stored command string when you press the switch. Type the following: ATS32 = 9 NOTE: If you usually use the voice/data switch for another purpose, you can include the execute stored command option (S32 = 9) in the stored command string. However, the total number of characters in the string may not exceed 30. If S32=9 is used with the stored command string, it over-writes any other S32 option. Once the communication session is over, you will have to reset S32 if you want to select another option. 4. Press the voice/data switch when you want to connect with the synchronous Host computer. You need not have your communications software loaded at the time. 5. After the call, restore the modem to asynchronous operations by powering it off and on again. ********* Answering To configure the modem for Answer mode using the voice/data switch, follow the instructions in the previous section, Dialing Out, but with these modifications: * Insert S0 = 1 in the stored command, Step 2. This sets the modem to Auto Answer. * Omit the Dial string shown in the same step (DT and phone number). If you don't wish to use a stored command and the voice/data switch, send the modem the appropriate configuration string, ending with &M1. The following command adapts the dial-out command example. Note again that all non-default settings follow the &F command. AT &F S0=1 &X1 &M1 The modem responds automatically to an incoming call, enters synchronous mode and, in this case (because it is set to &X1), waits for synchronous timing signals from your DTE. ********** Hanging Up The modem remains online until the remote modem disconnects or your software causes the DTE to drop the Data Terminal Ready signal (DTR). The Courier sends the NO CARRIER result code if result codes are enabled, and returns to asynchronous Command mode. **************************** Testing and Inquiry Commands The modem testing commands (&Tn) and inquiry commands (In) cannot be used when the modem is operating in synchronous mode. ********************** ENABLING REMOTE ACCESS Because synchronous equipment cannot use AT commands to configure modems, a special function was designed so the modem can receive AT commands remotely. To do this, the modem must be placed in remote access mode with the voice/data switch. Press and hold down the voice/data switch while powering on the modem. Pressing the switch during power-on causes the modem to perform its normal self-test, enable Auto Answer, enable Remote Access (by changing the S41 setting to 1), and disable password security. WARNING: If you enable remote access by pressing the voice/data switch while powering on the modem, previously set passwords will be erased. ________________________________________________________________________ DEDICATED AND LEASED LINE OPERATIONS The following operations apply in installations where the modem's phone line is not part of a public-access switched telephone network. Instead, the modem is connected to a special user-installed telephone line or a line that is leased from the telephone company. These lines are often referred to as dedicated (to a pair of modems) or private lines. In both types of installation there is a continuous point-to-point connection between two modems. No dialing of phone numbers is required. The modems may be in either Smart or Dumb mode (determined by the position of DIP switch 8). ******************************************* The User-Installed or Leased Telephone Line User-installed lines are most commonly 2-wire lines, similar to the 2-wire lines that connect residential phones to the public switched network. If you are leasing a line from the telephone company, request a 2-wire line, the type of line the modem is designed to work with. If the telephone company only makes a 4-wire line available, you'll need a 4-wire to 2-wire converter at each end of the connection. If the phone company does not install the converters, you will have to supply them. For optimal operations, we recommend that the physical length of these lines not exceed 5 miles. ***************** Setting the Modem If the Courier is set to &L1, as described in what follows, and the remote AT-compatible modem has a comparable setting, they automatically connect when they are powered on. They also reconnect, without any operator intervention, if a disturbance on the line is severe enough to break the connection. Set the modem as follows: 1. Set your terminal or communications software to the rate at which you want the modems to communicate. For example, use a terminal/software setting of 19.2K bps and, if both modems have the capability, they will connect at 14.4K bps. The following instructions assume that you are familiar with the guidelines on using the &B and &H commands (Chapter 3) and the &W command (Chapter 3). 2. Send the modem the following command: AT &B1 &S2 &H1 &L1 &W &B1 fixes the modem's computer interface rate at the same serial port rate you selected when setting up your communications software. &S2 causes the modem to send a Clear to Send (CTS) signal only after it sends the Carrier Detect (CD) signal, that is, only after it connects with the remote modem. (See the note that follows.) &H1 enables hardware (CTS) flow control. &L1 forces the modems off hook at power on and enables them to re-establish the connection should it be broken. &W writes the settings to nonvolatile memory (NVRAM) as power-on defaults. NOTE: We recommend using the &S2 setting to delay CTS until after the connection is made, as a precaution. If the modems are in the process of connecting or reconnecting, the Courier interprets any keyboard data entry, including an accidental key stroke, as a key-press abort, and hangs up. Delaying CTS until after carrier detection prevents this from happening, for example, if you are typing data to the remote modem when the modems momentarily disconnect and begin to reconnect. However, you have to set the modem for hardware flow control, &H1. If your software or machine does not support Clear to Send (CTS), don't include &S2 and &H1 in the command string as suggested above. Follow the Transmit Data flow control (&H) guidelines in Chapter 3. But keep in mind that if the modems fail to connect or reconnect, the reason could be a key-press abort. 3. Set the modem to load NVRAM settings at power-on, DIP switch 10 OFF. It does not matter if the modem is in Dumb or Smart mode (DIP switch 8). 4. Decide which modem is to be the calling modem and which the answering modem. Set the answering modem to Auto Answer, DIP switch 5 OFF, and the calling modem to Auto Answer suppressed, DIP switch 5 ON. 5. Power off and power on the modems. This initiates the new DIP switch settings and loads the power-on defaults, including &L1. The modems go off hook and establish the connection. NOTE: If the modems cannot restore the connection and you could not set the modem to &S2, the reason could be a key-press abort. If the problem persists, however, you may need to call your telephone company to have them check your line. Appendix G--Additional Operations CONTENTS HST Cellular Voice/Data (External Modems Only) Hewlett Packard 3000 Installations MI/MIC Operations (External Modems Only) _______________________________________________________________________ CELLULAR OPERATIONS This function applies to Dual Standard HSTs only. HST cellular modems can be used to answer or originate calls, but are proprietary. They can only connect with other U.S. Robotics Dual Standard modems with HST cellular capabilities. To enable cellular mode, load the &F3 template settings by typing the following command: AT &F3 To save this as your power-on/default setting, type this: AT &F3 &W The &F3 command sets the serial port rate to 19,200 bps, and formats the data for 8 bits, no parity and one stop bit. The ini-tialization string sent to the modem by loading this template is shown below. AT B1 X7 S10 = 30 &B1 &L2 &H1 &I0 &R2 * B1--enables HST modulation * X7--displays extended result codes including NO DIAL TONE, RINGING, NO ANSWER, and BUSY messages * &B1--locks the serial port rate so that it remains higher than the connection rate. * S10=30--sets the modem to wait 3 seconds after loss of carrier before hanging up. * &L2--enables cellular mode * &H1--enables hardware flow control * &I0--disables software flow control * &R2--sets the modem so it sends received data to the computer or terminal when the Ready To Send (RTS) signal is high, only if the computer or terminal supports RTS. The modem uses the U.S. Robotics proprietary HST cellular protocol to make connections. The call starts at 1200 bps, a V.42 error control connection is negotiated, then the modem switches to 4800 bps and begins measuring the line conditions. Depending on line conditions, the modem decreases or increases its connection rate, to a minimum speed of 300 bps and a maximum of 12K bps. If a connection terminates before data transfer is completed, the system tries to re-establish the link and complete the transfer. If a large number of blocks are being resent (shown by the ARQ LED flashing randomly; some software displays the blocks retransmitted in the file transfer window), you may want to reduce the packet size by doing the following: 1. Be sure DIP switch 9 is ON so that the modem remains online if it receives +++. 2. If DIP switch 9 is OFF, switch it to ON and reset the modem by issuing the ATZ command. 3. Send the modem the escape sequence by typing +++ so that the transmission is interrupted, and wait 1 second. 4. Type AT S33=1 to reduce the packet size. 5. Then type ATO so that the modem returns online and continues to transmit. NOTE: HST cellular connections can only be made with other U.S. Robotics modems in HST cellular mode. The modem cannot be used to place a voice or data call to another phone or modem when it is in this mode. __________________________________________________________________________ VOICE/DATA (EXTERNAL MODEMS ONLY) The voice/data switch is located on the modem's front panel. While the switch's primary function is to toggle back and forth between voice and data communications, this feature also allows you to perform other functions at the touch of a switch. Use Register S32 to select these functions, as shown in Table G.1. Additionally, the Courier modem allows you to use the voice/data switch to set the modem for remote access if attached to certain synchronous devices. This is described in Enabling Remote Access in Appendix F. NOTE: Use the voice/data switch when the modem is in Command mode (offline). If you press the switch while the modem is online, the modem hangs up and returns a NO CARRIER result code. ************************************************** VOICE/DATA OPERATIONS--S32=1, S32=2 or AT COMMANDS When you install the Courier, you have the option of plugging your phone into the second modular jack of the modem so it's available for voice calls. You can also switch between the phone and modem during a call. If the remote modem has handset exclusion, you can change from voice to data and back again, with or without issuing a command. Handset exclusion means that if the modem is using the phone line, your phone (handset) is automatically disconnected. However, if you keep the handset off hook, once you hang up the modem the handset takes over the phone line and you can use voice communications again. If the remote user does not have handset exclusion, you may not be able to switch back to voice mode successfully once you have switched to Data mode. The following instructions describe how to toggle voice/data communications with the switch. This is followed by instructions for doing the same thing with AT commands. If the remote user does not have a switch, he or she can follow the instructions for using the appropriate AT command. ******************************* Voice/Data Switch--S32=1, S32=2 1. Phone the other user to establish the bit rate, parity, word length and number of Stop bits the other person's modem accepts. (Both modems should be offline, in Command mode.) You and the other user must also agree on which modem will go off hook in Originate mode and which in Answer mode. The Courier is factory set to go off hook in Originate mode, S32=1. The Answer modem should have S32 set to 2. NOTE: If the stored command string command has been used (&ZC=s), the modem will default to S32=9, which executes the stored command string when the voice/data switch is pushed. Either party's device can be the originate or answer modem; it doesn't matter who made the phone call. But one modem must first enter Originate mode and the other then enter Answer mode. 2. Without hanging up the phone, press the voice/data switch. If S32 is set to 2, Answer mode, press the voice/data switch immediately after the remote user forces the remote modem off hook in Originate mode. 3. The other party should force the remote modem off hook in Answer mode by pressing the switch. If yours is the Answer modem (S32=2), the other party should press the voice/data switch immediately before you do so. 4. If the remote modem has handset exclusion, the remote user should also keep the phone off hook in order to switch back to voice later. If the remote modem doesn't have handset exclusion, you can try to switch back to voice later. Or, you both can hang up your phones as soon as the modems go off hook. *************************** Software Commands--ATD, ATA If your voice/data switch is set for a function other than voice/data operations and you don't wish to change it, use AT commands. 1. Call the other user to establish the bit rate, parity, word length and number of Stop bits the other person's modem accepts. Determine which modem will originate and which will answer. 2. If you are to originate the connection, type the following command: ATD NOTE: Be sure the modem is not set to X2, X4, X6 or X7, or it will return the NO DIAL TONE result code and hang up. 3. The other party must then have the remote modem go off hook in Answer mode. The following command is used to do this: ATA 4. If the remote modem also has handset exclusion, leave both phones off hook in case you wish to switch back again to voice after your data transfer. If the remote modem doesn't have handset exclusion, switching back to voice may not be successful. If you don't want to switch back to voice later, hang up both phones as soon as the modems go off hook. ************************************* ALLOWABLE VOICE/DATA AWITCH FUNCTIONS Use Register S32 to set the voice/data switch for the function you desire. The default is S32=1--pressing the switch forces the modem off hook in Originate mode. Pressing the switch when you power on the modem causes it to perform a power-on self-test. See Table G.1--S32 Functions below. NOTE: Some of the applications listed below require some sort of preconfiguration. Review the Chapter/Appendix referenced before using the Voice/Data switch function. Table G.1--S32 Functions S32 Value Voice/Data Switch Function Related Command 0 Disabled -- 1 Voice/Data--Originate Mode (Default*) ATD (Appendix G) 2 Voice/Data--Answer Mode ATA (Appendix G) 3 Redial Last Number ATDL (Chapter 4) 4 Dial Number Stored at position 0 ATDS0 (Chapter 4) 5 Auto Answer On/Off Toggle ATS0=0 or 1 (Chapter 4) 6 Reset Modem ATZ (Chapter 4) 7 Initiate Remote Digital Loopback AT&T6, S16=8 (Appendix H) 8 Busy Out Phone Line Toggle -- 9 Execute Stored Command (Default*) AT&ZC=s (Chapter 4, Appendix F, G) * The modem is shipped from the factory set at S32=9. If a command string has been stored (&ZC=s), the modem executes the stored command string when the voice/data switch is pushed. If no command string is stored, the modem still reports that S32=9, but actually behaves as if it is set to S32=1, Originate mode. __________________________________________________________________________ HEWLETT PACKARD INSTALLATIONS During error control connections, the Courier recognizes the ASCII ENQ/ACK characters exchanged between many Hewlett Packard host computers and their terminals. The HP host sends the terminal an ENQ character at predefined intervals, and sends no more data until the terminal responds with an ACK character. Courier modems manage this ENQ/ACK protocol so that communication is speeded up, thereby enabling HP terminals to achieve high speeds on dial-up lines. Special flow control settings, using the &I command, are required for HP users. These settings apply to ARQ connections only and to Courier modems set to either B0 or B1. Disregard other Courier flow control commands. Set the Courier to Host mode if it is attached to the host computer, or to Terminal mode if it is attached to a terminal, as follows: Host mode AT&I3 Terminal mode AT&I4 ___________________________________________________________________________ MI/MIC OPERATIONS (EXTERNAL MODEMS ONLY) Mode Indicate/Mode Indicate Common (MI/MIC) closure is required by some installations whose existing hardware does the dialing. The modems do not Auto Dial. In these situations, the modem must be forced off hook in Originate mode. This is done by shorting (closing) two of the pins (not Tip and Ring) in the phone connector. The modem is then ready to go online and accept data when it connects with the number dialed by the system equipment. Courier modems are shipped with MI/MIC disabled, that is, for normal use. To set the modems for MI/MIC closure, you must do two things: physically set jumpers on the modem’s printed circuit board, and enable bit 5 of Register S34 (ATS34=32 or ATS34.5=1). We recommend you then write that setting to NVRAM as a power-on default. Once you've set Register S34, have the system force the modem off hook by closing the MI/MIC leads in the phone line connector. The modem's OH (Off Hook) status light, or LED, goes on when the modem goes off hook. *************************** SETTIING THE MI/MIC JUMPERS You'll have to dismantle the modem case to set the two jumper switches on the printed circuit board, as follows: 1. Power off the modem and disconnect all of its cables. 2. Turn the modem upside down. Remove the two square vinyl feet near the back of the case, on either side of the bottom label's DIP switch diagram. Be careful to put the vinyl feet aside, upside down, where they won't become stuck to another object. 3. Remove the two Phillips screws located in the wells beneath the vinyl feet. 4. Gently pry off the plastic volume slide-switch cover. 5. Raise the back end of the case bottom until it is at about a 60 degree angle; lift it away from inside the front of the modem. Put the case bottom aside. 6. Locate the voice/data switch at the front of the modem. Lift up and remove the modem (printed circuit board), carefully easing the voice/data switch out of its opening in the front panel. 7. Turn the modem rightside up and locate jumper switches J4 and J6, 8. The jumpers are black shunts that cover two out of three upright metal contacts. As shown in the figure, set the jumpers so they cover the two contacts on each switch that are closest to the front panel. The third contact on each switch is exposed. 9. Replace the modem in the case top: ease the voice/data switch into the opening in the front panel and make sure the back of the board rests on the locator pins at the rear (from which you removed the screws). 10. Connect the modem's RS-232, power and phone cables, in that order (see Chapter 2). Be sure the phone cable is plugged into the jack closest to the center of the modem--the jack represented by the wall jack icon on the case bottom label. CAUTION: When you power on the modem there will be potentially hazardous voltage, particularly near the phone jacks. Do not touch the board when the power is on. 11. Power on the modem. Try MI/MIC closure. Check to see that the Off Hook (OH) status light goes on. If you dialed a number, listen for an answer tone from the remote modem. Then drop the DTR signal. The modem should go on hook and the OH status light should go off. 12. When you are sure the equipment is working correctly, disconnect the modem's RS-232, power and phone cables, and replace the bottom of the modem case. Ease the two nibs near the front corners into their openings in the front of the case top, guide the rectangular slot over the volume switch, and ease the back of the case bottom into place. Replace the two screws, the two vinyl feet, and the volume slide-switch cover. *************** TROUBLESHOOTING You may find that the modem does not respond to MI/MIC closure, which you can monitor by observing the LED. Or the modem may fail to go back on hook when the computer or terminal drops the Data Terminal Ready (DTR) signal. The probable reason for either of these conditions is that your phone equipment reverses MI/MIC polarity. It's possible to solve this problem by reversing the modem's MI/MIC wiring. You'll have to dismantle the modem case again and reset the two jumper switches on the printed circuit board, as follows: 1. Lift off the jumpers from J4 and J6. Reverse the positions. That is, on each switch, cover the center and rightmost contacts. Make sure the jumpers cover two contacts on each switch, or you'll disable the MI/MIC function. 2. Replace the modem in the case top: ease the voice/data switch into the opening in the front panel and make sure the back of the board rests on the locator pins at the rear (from which you removed the screws). 3. Reconnect the modem's RS-232, power and phone cables, in that order. Be sure the phone cable is plugged into the jack closest to the center of the modem--the jack represented by the wall jack icon on the case bottom label. CAUTION: When you power on the modem there will be potentially hazardous voltage, particularly near the phone jacks. Do not touch the board when the power is on. 4. Power on the modem. Try MI/MIC closure again. Check to see that the Off Hook (OH) status light goes on. If you dialed a number, listen for an answer tone from the remote modem. Then drop the DTR signal. The modem should go on hook and the OH status light should go off. 5. If closure is not working properly, review the steps in this section. Be sure the jumper switches are in the correct positions. If you still have problems, there may be a problem with the phone cable. Or there may be a problem with your hardware. 6. When the equipment is working correctly, disconnect the modem's RS-232, power and phone cables, and replace the bottom of the modem case. Ease the two nibs near the front corners into their openings in the front of the case top, guide the rectangular slot over the volume switch, and ease the back of the case bottom into place. Replace the two screws, the two vinyl feet, and the volume slide-switch cover. Appendix H--Modem Testing Testing is available with the &T command or Register S16. All loopback testing conforms to ITU-T Recommendation V.54. Earlier U.S. Robotics high speed modems, however, did not perform the &T test repertoire. Only one test can be performed at a given time. If you send a test command while the modem is in test mode, you'll receive an ERROR message. NOTE: Testing is not available when the modem is in synchronous mode: &M1, &M6, &M7. *************** Testing With &T The tests supported through the &T command include analog loopback, digital loopback and remote digital loopback. Users can key in their own data during testing, or use the modem's internal test pattern and error detector. In all cases, disable error control before testing. If the modem is detecting errors and retransmitting the affected data, your results will be invalid. During testing, the MR status light flashes. *********************** Ending a Test--&T0, S18 Issuing the &T0 command terminates a test. Alternatively, set Register S18 to a specified number of seconds, for example, S18=10. When the 10 seconds are up, the modem automatically ends the test and returns to Command mode. If the test was Analog Loopback, the &T0 command hangs up the modem. If the test was Digital or Remote Digital Loopback, issue an ATH command to hang up the modem, or an ATZ command to hang up the modem and reset it to its defaults. NOTE: If you use the S18 test timer, but in the process of testing you issue an ATZ command, S18 resets to zero and the timer is disabled. You cannot store a value for S18 in nonvolatile memory; its power-on and reset default is always zero. ************************* Analog Loopback--&T1, &T8 This test checks the operation of the modem's transmitter and receiver. There are two analog loopback options. The first, &T1, involves your typing data that you can verify at your screen. The second option, &T8, is an internal self-test that does not involve the keyboard or screen. It isolates the modem from the computer interface to give you a more specific result. NOTE: Dual Standard modems must be set to B0 (default) or tested at 2400 bps or lower to avoid HST asymmetrical modulation at higher speeds. *** &T1 1. If you are testing an HST or Dual Standard modem, set your terminal or software to 2400 bps. 2. The modem must be in Command mode. If you wish, set Register S18 as a test timer, as explained earlier. 3. Send the modem the following command: AT &M0 &T1 The modem disables error control, enters analog loopback (AL) mode, and sends a CONNECT message. The MR status light flashes. 4. Type recognizable data so that you can verify it when it is looped back to the screen. 5. End the test. If you set S18, the modem automatically stops the test at the timeout, exits AL mode and responds OK. If you didn't set Register S18, wait one second and type +++ to bring the modem back to Command mode. If DIP switch 9 is OFF, the modem also hangs up and ends the test. If DIP switch 9 is ON, type AT&T0 to end the test. Or send either ATH or the command that resets the modem, ATZ. The latter two commands end the test and hang up the modem. The modem responds OK. If the modem sends an ERROR message, you have issued an invalid command. 6. If there were no errors, reset the modem to &M4, for error control, unless you've issued the ATZ reset command. NOTE: If the modem is in online-command mode, that is, still connected to a remote modem, and you send it an &T1 or &T8 command, it drops the call, enters AL mode, sends a CONNECT result and waits for loopback characters. *** &T8 This AL option causes the modem to send an internal test pattern to its transmitter and loop it back to the receiver. An internal error detector counts any errors and, when the test is ended, sends the number of errors or 000 (no errors) to the screen. Since you don't type anything during this test, and the modem does not send anything to the screen, this option verifies only the modem. If there are no errors but your problem continues, it may be at the computer interface. 1. If you are testing an HST or Dual Standard modem, set your terminal or software to 2400 bps. 2. The modem must be in Command mode. If you wish, set Register S18 as a test timer, as explained earlier. 3. Send the modem the following command: AT &M0 &T8 The modem disables error control and enters AL mode. The MR status light flashes. The modem sends its internal test pattern to the transmitter, and loops the pattern back to the receiver. You will not see any data on your screen. 4. End the test. If you set S18, the modem automatically stops the test at the timeout. If you didn't set Register S18, type AT&T0 to end the test. Or use ATH or the command that resets the modem, ATZ. Both of the latter end the test and hang up the modem. The modem hangs up and returns a three-digit code, followed by OK. A code of 000 indicates no errors were found. A code of 255 indicates 255 or more errors. An ERROR message indicates that you issued an invalid command. 5. If there were no errors, reset the modem to &M4 for error control unless you issued the ATZ command. *** &T2 This option is reserved. ********************* Digital Loopback--&T3 If your modem has passed the AL test, this test can help you locate a problem with a remote modem or the telephone channel. NOTE: This test requires the modem to establish a connection and return to online-command mode in response to the +++ escape code. DIP switch 9 must be set ON so that the modem does not hang up on receipt of the escape code. After you change the switch, issue ATZ to the modem to initiate the new setting. As with AL testing, HST and Dual Standard modems should be tested at 2400 bps or lower. 1. Set the modem to &M0, to disable error control. HST and Dual Standard modems should be set to 2400 bps or lower to avoid asymmetrical modulation at higher speeds. Establish a connection with the remote modem. 2. Bring the modem back to Command mode with the +++ escape code. Then send it the AT&T3 command. The modem enters DL mode and the MR status light flashes. 3. The remote user should type a short message. It will be looped back by your modem's transmitter for verification on the remote screen. You will not see the message or any other data. 4. When the remote user has completed the test, issue the AT&T0 command to end the test. Or send either ATH or the command that resets the modem, ATZ. The latter two commands end the test and hang up the modem. The modem responds OK. If the modem sends an ERROR message, you have issued an invalid command. 5. Reset DIP switch 9 OFF if you normally use the factory default. Reset the modem to &M4 unless you used the reset command, ATZ. ******** &T4, &T5 The &T4 option causes the modem to grant a remote modem's request for a Remote Digital Loopback test. The &T5 option cancels &T4, and the modem fails to recognize such a request. This is the default so that your modem isn't subject to another user calling and tying up your modem without your permission. ********************************* Remote Digital Loopback--&T6, &T7 This test, like the local digital loopback test, verifies the condition of both modems and the phone link. The request for and granting of Remote Digital Loopback testing requires that both modems use ITU-T V.22 standard signaling. The test must be performed at 2400 bps or lower. If the remote modem does not have the capability or is not set to respond (&T4), you will get an ERROR result code. As with Analog Loopback, there are two Remote Digital Loopback options. If you select &T6, you send keyboard data to the modem and verify it when it is returned over the phone lines and to your screen. If you select &T7, the modem sends its internal test pattern and returns an error count to your screen. NOTE: Both test options require the modem to establish a connection and return to online-command mode in response to the +++ escape code. DIP switch 9 must be set ON so that the modem does not hang up on receipt of the escape code. If necessary, set the switch ON and then issue the ATZ command to the modem to initiate the new switch setting. *** &T6 1. Set the software to 2400 bps or lower. Set the modem to &M0. If you wish, set the S18 timer. Establish a connection with the remote modem. If you haven't already done so, arrange with the remote user to cooperate with your testing and, if necessary, set the remote modem to acknowledge the RDL request. For example, older U.S. Robotics high speed modems need to be set to S16=8. 2. Bring the Modem back to Command mode with the +++ escape code. Send it the AT&T6 command. The modem enters RDL mode and the MR status light flashes. 3. Type a short message. It will be looped back to your modem by the remote modem and to your screen for verification. (The remote user will not see your data.) 4. End the test. If you set Register S18 the modem automatically ends the test when the test timeout is reached. If you didn't set S18, type AT&T0 to end the test. Or send either ATH or the command that resets the modem, ATZ. The latter two commands end the test and hang up the modem. The modem responds OK. If you issue an invalid command, the modem sends an ERROR message. Data errors indicate a problem with the remote modem or the phone link. If you have not performed analog loopback testing with your modem, the problem may also lie with your modem. 5. Reset DIP switch 9 OFF unless you normally set that switch ON, and issue ATZ to the modem to initiate the new setting. Reset the modem to &M4 unless you used the reset command, ATZ. *** &T7 This test option causes the modem to send an internal test pattern through the Remote Digital Loopback. An internal error detector counts any errors and, when the test is ended, sends the number of errors or 000 (no errors) to the screen. You don't need to type anything during this test. The modem sends only its final error count to your screen. 1. Set the software to 2400 bps or lower. Set the modem to &M0. If you wish, set the S18 timer. Establish a connection with the remote modem. If you haven't already done so, arrange with the remote user to cooperate with your testing and, if necessary, set the remote modem to acknowledge the RDL request. For example, older U.S. Robotics high speed modems need to be set to S16=8. 2. Bring the modem back to Command mode with the +++ escape code. Then send it the AT&T7 command. The modem enters RDL mode and the MR status light flashes. The modem sends its internal test pattern to the remote modem, which loops it back to your modem. You will not see the data on your screen. 3. End the test. If you set S18, the modem automatically stops the test when the timer times out. If you didn't set Register S18, type AT&T0 to end the test. Or send either ATH or the command that resets the modem, ATZ. The latter two commands end the test and hang up the modem. The modem responds OK. If you issue an invalid command, the modem sends an ERROR message. When you terminate the test, the modem returns a three-digit code, followed by OK. A code of 000 indicates no errors were found. A code of 255 indicates 255 or more errors. If you've performed an Analog Loopback and know your modem is working properly, errors indicate a problem with either the phone connection or the remote modem. 4. Reset DIP switch 9 OFF unless you normally operate with it ON. Issue an ATZ command to initiate the new switch setting. Reset the modem to &M4 unless you've sent it the ATZ reset command. ************************* TESTING WITH REGISTER S16 Register S16 is a bit-mapped register with the following bit functions: Bit Value Function 0 1 Analog Loopback (AL) 1 2 Dial Test 2 4 Test Pattern 3 8 Remote Digital Loopback (RDL) NOTE: Earlier U.S. Robotics modems require bit 3 to be enabled in order to grant RDL to a remote modem. The modem now requires its default &T4 setting instead. To perform RDL with a U.S. Robotics modem that does not use the &T test repertoire, that modem should be set to S16=8 before it can grant RDL testing. **************************** Analog Loopback (AL)--S16=1D As with the &T AL test, do not attempt this test under error control. HST and Dual Standard modems should be tested at 2400 bps or lower, to avoid asymmetrical modulation at higher speeds. To use the modem's Test Pattern (S16, bit 2) instead of typing your own data, see Test Pattern--S16=4 later in this appendix. 1. To initiate testing, type AT&M0S16=1D. The modem disables error control, enters AL mode and sends a CONNECT result code. The MR status light flashes. 2. Type data to the modem for the modem to transmit, loop to its receiver, and output to the screen. An alternative is to use the Test Pattern, described later. 3. End the test by not typing anything for one second, then typing three pluses (+++), and waiting another second. This forces the modem back to Command mode. If DIP switch 9 is OFF, the modem exits AL mode and returns to Command mode. If DIP switch 9 is ON, the modem maintains the connection when it receives the +++ escape code. Issue the ATH command to end AL mode. 4. Reset the modem to Data mode, S16=0, and error control (&M4), or issue the ATZ (reset) command. **************** Dial Test--S16=2 The Dial Test is used for factory testing the frequencies of tone values. When S-Register 16 is set to 2 and a single tone is dialed (e.g., ATD7 ), the modem continues to transmit that tone until you type another Carriage Return. ******************* Test Pattern--S16=4 The test pattern can be used instead of your typed data during Analog Loopback (AL) or Remote Digital Loopback (RDL), using &T commands or S16. The test pattern is available at all speeds. At 300 bps, the modem's serial port rate must be fixed (&B1) and the link rate fixed at 300 bps (&N1). At rates over 9600 bps, just set the modem for a fixed serial port rate (&B1). To use the test pattern during AL testing with S16, type the following command. The test pattern is sent through the loopback. AT&M0S16=5D To use the test pattern during RDL testing with S16, type the following command: AT&M0S16=12 To use the test pattern with the &T AL or RDL tests, insert the test pattern command, S16=4, before issuing the test command. The first of the following commands initiates AL, the second RDL: ATS16=4&T1 ATS16=4&T6 The test pattern alone (ATS16=4) is used for testing equipment and the phone line. When S16 is set to 4, the modem transmits the test pattern upon connection with a remote modem. Ending Testing with the Test Pattern Pressing any character key cancels all test pattern tests and hangs up the modem. If you used Register S16, be sure to reset Register S16 to Data mode when you reset the modem to its error control defaults, for example, ATZ or AT&M4S16=0. ****************************** Remote Digital Loopback--S16=8 Responding Modem The responding modem must be ready to act on the Courier's RDL request. U.S. Robotics high speed modems should be set to &T4. If they do not have &T testing capability, they should be set to S16=8. Initiating Modem 1. If DIP switch 9 is OFF, set it ON so that it does not hang up on receipt of the +++ escape code. Issue an ATZ command to initiate the new switch setting. 2. Set the software to 2400 or 1200 bps. The ITU-T-specified RDL signals are defined only for connections at 2400 or 1200 bps. 3. Disable error control by setting the modem to &M0. Then establish a connection with the remote modem. 4. Bring the modem back to Command mode by sending it the escape code: one second of no data, three pluses (+++), and another second of no data. 5. When the OK result code appears, send the modem the following command: ATS16=8 O The modem enters RDL mode (S16=8), the MR status light flashes, and the modem goes back online (O command). Then it transmits the ITU-T-defined RDL signals, causing the remote modem to enter RDL mode. 6. Type any data at the keyboard. (Or send the test pattern.) 7. To end the test, send the modem the +++ escape code again to bring it back to Command mode. 8. When the modem sends the OK result, reset the modem to Data mode with the following command: ATS16=0 The modem signals the responding modem that RDL testing is over. Terminate the call as you normally would, and reset the modem to its normal error control setting, &M4 or &M5. Or, if you wish to resume data transmission with the remote modem, add the O command to the ATS16=0 string to return the modem online. Keep in mind, however, that error control is disabled. Because error control is negotiated during the connection sequence, its status cannot be changed until the modem is back on hook and in Command mode. Appendix I--Software Upgrades The Courier V.34 modem is software upgradable. You can download upgrades from the USR Bulletin Board Service (BBS) to obtain maintenance fixes or new features. We suggest you retain a copy of the most recent upgrade on disk so you can download it to your modem again, should the modem lose its code for any reason. The software download program requires DOS version 3.0 or higher and may be run from the DOS shell under Microsoft Windows. **************** Call the USR BBS 1. Call the USR BBS: ATDT 708 982 5092 2. Unless you are running an ASCII-based communications program, answer YES at the graphics prompt when you connect to the BBS. 3. Press Enter with each prompt until you come to the main menu. ************************* Download the Upgrade File 1. At the command line of the main menu, type F (File) and press Enter. Select area 5 (Courier) from the file area menu The most recent zipped files will display. 2. Use the Enter key to scroll through the list and use the spacebar key to highlight a file. Scroll through the list and highlight the file named USRSDL.EXE. Press Enter when it is highlighted to flag the file for download. 3. Press Enter to go back to the main menu. 4. At the command line on the main menu, type D and press Enter to initiate a download. 5. Answer the download prompts according to your system requirements. The file will be downloaded to the directory specified in your communications software. 6. When the file transfer is complete and you are ready to leave the BBS, type G (Goodbye) from the main menu. ****************** Upgrade your Modem NOTE: Your modem must be turned on for the following operation. 1. At the DOS prompt of the directory where your copy of the file has been downloaded, type USRSDL and press Enter. The zipped file will self-extract several files onto your computer hard disk. 2. Type SDL and press Enter. The .EXE file checks the code embedded in itself. If there is a problem, an error message appears and the operation is terminated. If you receive an error message, download the file again. 3. A screen appears with default COM port information. If you want to alter the defaults, use the guidelines below. /c=n Enter this command to select one of four predefined COM ports on an IBM-compatible PC. Valid entries for n are 1, 2, 3, and 4. The default is COM 2. If you change the COM port setting, a compatible IRQ will be displayed. /i=n Enter this command to set up a custom port. It specifies which IRQ (interrupt request) the COM port will use to interrupt the processor for service. Valid entries for n are 2, 3, 4, 5, and 7. The default is IRQ 3. /a=n Enter this command to specify a port address, where n is the hexadecimal address of a custom port only. /b=n Enter this command to specify the bit rate at which the COM port will communicate with the modem. Valid entries for n are 9600, 19200, 38400, 57600, and 115200. The default is 57600 bps. /q This command allows you to shut off most of the screen display as the program upgrades your modem code for batch-mode execution. You will not be prompted to accept settings. /? This command displays a help screen. 4. A prompt asks if you want to "Download Using These Settings? (Y/N)." Type Y if you want to continue. Type N if you want to abort the operation. NOTE: This is the only opportunity you will have to abort the operation. 5. Once you have accepted the settings, the software download will begin. During this operation, the Modem Ready (MR) LED goes out. 6. When the operation has successfully completed, the "Modem reports download successful" message displays and the MR LED lights up again. *************** Troubleshooting If your modem indicates an error, try running the SDL program at a lower serial port rate. If your computer doesn’t have a 16550 UART, a slower serial port rate can make all the difference. You can also try running the program on a different PC. An idiosyncracy of an off-brand PC or an uncommon version of DOS my hang up the SDL program. Appendix J--Glossary Adaptive Speed Leveling (ASL) Courier V.32 bis and V.32 terbo modems detect improved line conditions and shift upward again to the next higher speed. The modems at both ends of the connection adapt independently, each detecting and adjusting to line conditions. ASL keeps the modems online, always operating at the highest possible speed, and constantly ensuring data integrity. Analog Loopback A modem self-test in which data from the keyboard is sent to the modem's transmitter, modulated into analog form, looped back to the receiver, demodulated into digital form, and returned to the screen for verification. Analog Signals Continuous, varying waveforms such as the voice tones carried over phone lines. Contrast with digital signals. Answer Mode A state in which the modem transmits at the predefined high frequency of the communications channel and receives at the low frequency. The transmit/receive frequencies are the reverse of the calling modem which is in Originate mode. Application (application program) A computer program designed to perform a specific function, such as a word processor or a spreadsheet. ARQ Automatic Repeat Request. A general term for error control protocols which feature error detection and automatic retransmission of defective blocks of data. See HST, MNP, and V.42. ASCII American Standard Code for Information Interchange. A 7-bit binary code (0's, 1's) used to represent letters, numbers, and special characters such as $, !, and /. Supported by almost every computer and terminal manufacturer. Asymmetrical Modulation A duplex transmission technique which splits the communications channel into one high speed channel and one slower channel. During a call under asymmetrical modulation, the modem with the greatest amount of data to transmit is allocated the high speed channel. The modem with less data is allocated the slow, or back channel (450 bps). The modems dynamically reverse the channels during a call if the volume of data transfer changes. Asynchronous Transmission Data transmission in which the length of time between transmitted characters may vary. Because the time lapses between transmitted characters are not uniform, the receiving modem must be signaled as to when the data bits of a character begin and when they end. The addition of Start and Stop bits to each character serves this purpose. Auto Answer A feature in modems enabling them to answer incoming calls over the phone lines without the use of a telephone receiver. Auto Dial A feature in modems enabling them to dial phone numbers over the phone system without the use of a telephone transmitter. Baud Rate The number of discrete signal events per second occurring on a communications channel. Although not technically accurate, baud rate is commonly used to mean bit rate. Binary Digit A 0 or 1, reflecting the use of a binary numbering system (only two digits). Used because the computer recognizes either of two states, OFF or ON. Shortened form of binary digit is bit. Bisync Binary Synchronous Control. An earlier protocol developed by IBM for software applications and communicating devices operating in synchronous environments. The protocol defines operations at the link level of communications, for example, the format of data frames exchanged between modems over a phone line. See Protocol, HDLC, SDLC. Bit Rate The number of binary digits, or bits, transmitted per second (bps). Communications channels using telephone channel modems are established at set bit rates, commonly 300, 1200, 2400, 4800, 9600, and 14400. BPS The bits (binary digits) per second rate. Buffer A memory area used as temporary storage during input and output operations. An example is the modem's command buffer. Another is the Transmit Data flow control buffer used for flow control and to store copies of transmitted frames until they are positively acknowledged by the receiving modem. Byte A group of binary digits stored and operated upon as a unit. A byte may have a coded value equal to a character in the ASCII code (letters, numbers), or have some other value meaningful to the computer. In user documentation, the term usually refers to 8-bit units or characters. 1 kilobyte (K) is equal to 1,024 bytes or characters; 64K indicates 65,536 bytes or characters. Call Indicate A call originating tone defined by ITU-T recommendation V.8. Carrier A continuous frequency capable of being either modulated or impressed with another information-carrying signal. Carriers are generated and maintained by modems via the transmission lines of the telephone companies. CCITT Formerly, an international organization that defined standards for telegraphic and telephone equipment. It has been incorporated into its parent organization, International Telecommunication Union (ITU). Telecommunication standards are now covered under Telecommunications Standards Sector (TSS). ITU-T replaces CCITT. For example, the Bell 212A standard for 1200 bps communication in North America was referred to as CCITT V.22. It is now referred to as ITU-T V.22. Character A representation, coded in binary digits, of a letter, number, or other symbol. Characters Per Second A data transfer rate generally estimated from the bit rate and the character length. For example, at 2400 bps, 8-bit characters with Start and Stop bits (for a total of ten bits per character) will be transmitted at a rate of approximately 240 characters per second (cps). Some protocols,