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Troubleshooting: Multi-Tech MT5634ZBA User's Guide

Introduction • No Indicators Light • Does Not Respond to Commands • Dials But Cannot Connect • Disconnects While Online • Does Not Connect When Answering • Slow File Transfer • Lost Data • Garbage Characters • Caller ID Doesn't Work • Fax and Data Programs Can't Run at the Same Time

Introduction

Your modem was thoroughly tested at the factory before it was shipped. If you are unable to make a successful connection, or if you experience data loss or garbled characters during your connection, it is possible that the modem is defective. However, it is more likely that the source of your problem lies elsewhere. The following symptoms are typical of problems you might encounter:

• None of the indicators light.
• The modem does not respond to commands.
• The modem dials but is unable to make a connection.
• The modem disconnects while online.
• The modem cannot connect when answering.
• File transfer is slower than it should be.
• Data is being lost.
• There are garbage characters on the monitor.
• The modem doesn't work with Caller ID.
• Fax and data programs can't run at the same time.

If you experience problems, please check the following possibilities before calling Technical Support.

None of the Indicators Light

When you turn on the modem, the LED indicators on the front panel should flash briefly as the modem runs a self-test. If the LEDs remain off, the modem is probably not receiving power.

• Make sure the modem's power switch is on, especially if you normally turn on the modem by turning on a power strip.

• If the power adapter is plugged into a power strip, make sure the power strip is plugged in and its power switch is on.

• Make sure the power adapter is firmly connected to the modem and to the wall outlet or power strip.

• If the power strip is on and the modem switch is on, try moving the modem power adapter to another outlet on the power strip.

• Test that the outlet is live by plugging a lamp into it.

• The modem or power adapter may be defective. If you have another MT5634ZBA modem, try swapping modems. If the problem goes away, the first modem or power adapter may be defective. Call Technical Support for assistance.

CAUTION: Do not under any circumstances replace the power supply module with one designed for another product, as it can damage the modem and void your warranty.

The Modem Does Not Respond to Commands

• Make sure the modem is plugged in and turned on. (See None of the indicators light.)

• Make sure you are issuing the modem commands from a data communication program, either manually in terminal mode or automatically by configuring the program. (You cannot send commands to the modem from the DOS prompt.)

• Make sure you are in terminal mode in your data communication program, then type AT and press ENTER. If you get an OK response, your connections are good, and the problem likely is in the connection setup in your communication program.

• Try resetting your modem by turning it off and on. If you are using a DOS or Windows 3.1 communication program, make sure the initialization string includes &F as the first command, to cancel any "leftover" command that could affect the modem's operation.

• If you don't get an OK, the problem may still be in the communication program. Make sure you have done whatever is necessary in your software to make a port connection. Not all communication programs connect to the COM port automatically. Some connect when the software loads and remain connected until the program terminates. Others can disconnect without exiting the program. The modem's TR indicator lights to show that the software has taken control of the modem through the COM port.

• Your communication program settings might not match the physical port the modem is connected to. The serial cable might be plugged into the wrong connector—check your computer documentation to make sure. Or you might have selected a COM port in the program other than the one the modem is physically connected to—compare the settings in the program to the physical connection.

• If the modem is on, the cable is plugged into the correct port, the communication program is configured correctly, and you still don't get an OK, the fault might be in the serial cable. Make sure it is firmly connected at both ends.

• Is this the first time you have used the cable? If so, it may not be wired correctly. Check the cable description on the package to make sure the cable is the right one for your computer.

• Peripheral expansion cards, such as sound and game cards, can include a serial port preconfigured as COM1 or COM2. The extra serial port, or the card itself, may use the same COM port, memory address, or interrupt request (IRQ) as your communications port. Be sure to disable any unused ports.

• The modem might be defective. If you have another MT5634ZBA modem, try swapping modems. If the problem goes away, the first modem is possibly defective. Call Technical Support for assistance.

The Modem Dials But Cannot Connect

There can be several reasons the modem fails to make a connection. Possibilities include:

• lack of a physical connection to the telephone line.
• a wrong dial tone.
• a busy signal.
• a wrong number.
• no modem at the other end.
• a faulty modem, computer, or software at the other end.
• incompatibility between modems.

You can narrow the list of possibilities by using extended result codes. Extended result codes are enabled by default. If they have been disabled, include V1X4 in the modem's initialization string, or in terminal mode type ATV1X4 and press ENTER. When you dial again, the modem will report the call's progress.

• If the modem reports NO DIALTONE, check that the modem's telephone line cable is connected to both the modem's LINE jack (not the PHONE jack) and the telephone wall jack. If the cable looks secure, try replacing it. If that doesn't work, the problem might be in your building's telephone installation. To test the building installation, plug a telephone into your modem's telephone wall jack and listen for a dial tone. If you hear a dial tone, your modem might be installed behind a company phone system (PBX) with an internal dial tone that sounds different from the normal dial tone. In that case, the modem might not recognize the dial tone and might treat it as an error. Check the PBX manual to see if you can change the internal dial tone; if you can't, change your modem's initialization string to replace X4 with X3, which will cause the modem to ignore dial tones.

NOTE: X3 is not allowed in some countries, such as France and Spain.

• If the modem reports BUSY, the other number might be busy, in which case you should try again later, or it might indicate that you have failed to add a 9, prefix to the phone number if you must dial 9 for an outside line.

NOTE: If you must dial 9 to get an outside line, the easiest way to dial it automatically is to include it in the modem's dial prefix, e.g., ATDT9,. Note the comma, which inserts a pause before the number is dialed. By inserting 9, into the dial prefix, you do not have to include it in each directory entry.

• If the modem reports NO ANSWER, the other system has failed to go off-hook, or you might have dialed a wrong number. Check the number.

• If the modem reports NO CARRIER, the phone was answered at the other end, but no connection was made. You might have dialed a wrong number, and a person answered instead of a computer, or you might have dialed the correct number but the other computer or software was turned off or faulty. Check the number and try again, or try calling another system to make sure your modem is working. Also, try calling the number on your telephone. If you hear harsh sounds, then a modem is answering the call, and the modems might be having problems negotiating because of modem incompatibilities or line noise. Try connecting at a lower speed.

The Modem Disconnects While Online

• If you have Call Waiting on the same line as your modem, it can interrupt your connection each time someone tries to call you. If you have Call Waiting, disable it before each call. In most parts of North America, you can disable Call Waiting by preceding the telephone number with *70 (check with your local telephone company).

NOTE: You can automatically disable Call Waiting by including the disabling code in the modem's dial prefix (e.g., ATDT*70,—note the comma, which inserts a pause before the number is dialed). To change the dial prefix in Windows Terminal, select Settings | Modem Commands. To change it in Windows 95 HyperTerminal, select Connect from the Call menu, click Dialing Properties, check This location has Call Waiting, and select the correct code for your phone service.

• If you have extension phones on the same line as your modem, you or someone else can interrupt the connection by picking up another phone. If this is a frequent problem, disconnect the extension phones before using the modem, or order a separate line for the modem.

• Check for loose connections between the modem and the computer, the telephone jack, and AC power.

• You might have had a poor connection because of line conditions or the problem might have originated on the other end of the line. Try again.

• If you were online with a BBS or an online service like CompuServe, it might have hung up on you because of lack of activity on your part or because you exceeded your time limit for the day. Try again.

The Modem Cannot Connect When Answering

• Autoanswer might be disabled. Turn on autoanswer in your datacomm program or send the command ATS0=1 (ATS0=2 if you have Caller ID service) to your modem in terminal mode.

File Transfer Is Slower Than It Should Be

• If you are using a slow transfer protocol, such as Xmodem, try Zmodem or Ymodem/G instead.

• Is your line noisy? If there is static on your line, the modem has to resend many blocks of data to insure accuracy. You must have a clean line for maximum speed.

• Are you downloading a compressed file with MNP 5 hardware compression enabled? Since hardware data compression cannot compress a file already compressed by an archiving program, the transfer can be marginally slower with data compression enabled than with it disabled.

• Does your Internet service provider (ISP) use the same 56K protocol as your modem? The default setting of your modem is to connect using either the K56flex or the V.90 protocol, depending on which one the ISP modem is using. If your ISP uses the X2 protocol, the maximum speed you will be able to connect at is 33,600 bps. Check with your ISP to see which protocols it supports.

• Try entering the I11 command in online mode or the &V in command mode to display information about the last connection, making a screen print of the connection statistics, and checking for parameters that might be unacceptable.

Data Is Being Lost

• If you are using data compression and a high speed serial port, set the serial port baud rate to two to four times the data rate.

• Your UART might not be reliable at serial port speeds over 9600 bps or 19,200 bps. Turn off data compression, reset your serial port speed to a lower rate, or replace your serial port with a faster one.

• Make sure the flow control method you selected in software matches the method selected in the modem.

• If you are running under Windows 3.1 and have a 16550AFN UART, you might need to turn on the 16550's data buffers and/or replace the Windows serial driver, COMM.DRV.

• Try entering the I11 command in online mode or the &V1 command in command mode to display information about the last connection, making a screen print of the connection statistics, and checking for parameters that might be unacceptable.

There Are Garbage Characters on the Monitor

• Your computer and the remote computer might be set to different word lengths, stop bits, or parities. If you have connected at 8-N-1, try changing to 7-E-1, or vice-versa, using your communication software.

• You might be experiencing line noise. Enable error correction, if it is disabled, or hang up and call again; you might get a better connection the next time.

• At speeds above 2400 bps, the remote modem might not use the same transmission or error correction standards as your modem. Try connecting at a slower speed or disabling error correction. (With no error correction, however, line noise can cause garbage characters.)

• Try entering the I11 command in online mode or the &V1 command in command mode to display information about the last connection, making a screen print of the connection statistics, and checking for parameters that might be unacceptable.

The Modem Doesn't Work with Caller ID

• Caller ID information is transmitted between the first and second rings, so if autoanswer is turned off (S0=0) or if the modem is set to answer after only one ring (S0=1), the modem will not receive Caller ID information. Check your initialization string, and if necessary change it to set the modem to answer after the second ring (S0=2).

• Make sure that you have Caller ID service from your telephone company.

Fax and Data Programs Can't Run at the Same Time

• Communications devices can be accessed by only one application at a time. Under DOS or Windows 3.1x, you can run either your fax software or your datacomm software, but not both at the same time, unless you have a special communication device management application. In Windows 95, 98, and NT 4.0, you can have separate data and fax communication applications open at the same time, but they cannot use the same modem at the same time.

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