APPENDIX D. PROBLEMS AND SOLUTIONS You may occasionally encounter one of the problems listed here. They are divided into two categories: before and during the exchange of user information over the data link. Before Establishment of the Data Link Your modem . . . Doesn't answer the phone or go off hook to dial a number Review the Settings Supplement that came with the modem or 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 DOWN, for command set recognition. If the switch is UP, power off the modem, set the switch DOWN, and power on the modem again. Try typing AT again. 5. Check that DIP switch 3 is DOWN, for result code display, and that DIP switch 2 is UP, 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 the Settings Supplement that came with the modem or your communi- cations 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 Appendix B-1, Appendix B-3, Quad switch, and 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 DOWN at the factory for Carrier Detect (CD) override, but your system may require that the override be turned OFF. Review your terminal's manual, the Settings Supplement that came with the modem 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, acts if 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. 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 Chapter 7. 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. 2. Check to see that your modem is at the correct Bn setting to connect with either an HST modem (B1 setting) or V.32 modem (B0 setting). Type ATI4 for a display of the Courier's current settings and, if necessary, send the modem the correct setting. 3. 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. 4. Depending on your model, make sure the modem at the other end of the line is HST compatible, V.32 bis 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. 5. 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 DTE rate (&B1) and your software is fixed at 19.2K or 38.4K 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 bis 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 dis- able 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 UP (factory setting), the modem hangs up when it returns to Command mode, and you'll have to call again. If DIP switch 9 is DOWN, 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 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 USRobotics. 3. If your dealer can't clear up your difficulties, call the USRobotics Technical Support Department at 800- 982-5151, or send a Fax to 708-982- 0823. Our Service Representatives will be happy to give you assistance over the phone Monday through Friday from 7:30 a.m. to 6:00 p.m. (Central Time Zone). 4. If necessary, the Service Representative you talk to may 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 d. Please note that USRobotics will not accept packages sent COD, so be sure to send the modem postage paid. e. USRobotics will repair your modem and return it to you via United Parcel Service.