Multi-Tech Systems PN S000408C manual Modem Does Not Respond to Commands

Chapter 7 – Troubleshooting

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 data communication software, either manually in terminal mode or automatically by configuring the software.

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

•Try resetting your modem by turning it off and on.

•If you don’t get an OK, the problem may still be in the communication software. 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 software settings may not match the physical port the modem is connected to. The serial cable might be plugged into the wrong connector—check your computer documen- tation to make sure. Or you might have selected a COM port in your software other than the one the modem is physically connected to—compare the settings in your software to the physical connection.

•If the modem is on, the cable is plugged into the correct port, the communication software 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 packaging to make sure the cable is the right one for your computer.

•Peripheral expansion cards, such as sound and game cards, might 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 communication port. Be sure to disable any unused ports.

•The serial port might be defective. If you have another serial port, install the modem on it, change the COM port setting in your software, and try again.

•The modem might have a problem beyond the scope of this user guide. If you have another Multi- Tech modem, try swapping modems. If the problem goes away, call Technical Support.

The Modem Cannot Connect When Dialing

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 enter ATV1X4 and press ENTER. When you dial again, the modem reports 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.

Multi-Tech Systems, Inc. MT5600BA-V92 User Guide 40