Digital Modem Installation Guide

72 Troubleshooting

CTA 500

On Line Guide P0873832 Issue 05

¥ If the cable is faulty or the ICS is down, the attached phone will

also not work.

AT command problem?

The CTA 500

does not respond to AT commands sent from

your PC.

¥ Make sure that your PC, terminal or other DTE is conÞgured

correctly.

¥ Check the DTE connection. If the DTE is conÞgured as a DCE

you may need a null modem cable.

¥ Check that your PC or DTE is conÞgured to expect CD and CTS

signals. See ÒSerial Interface Control LinesÓ on page 56 for

more information.

¥ Check that the CTA 500dm is in the command mode.

¥ Check that your PC or DTE is conÞgured to provide a DTR

signal. See ÒSerial Interface Control LinesÓ on page 56 for more

information.

¥ If the LED is ßashing quickly, refer to the ConÞguration section

of this document.

¥ Check that the CTA 500dm serial port is set to the correct baud

rate (115200 is required for all cases except during a software

upgrade) using ÒSerial Interface RateÓ on page 54.

Echoed AT commands from the CTA 500

do not appear

correctly on your PC, but the response messages appear

correctly.

¥ Check the echo option on your PC.

¥ Disable echo if your PC displays duplicate characters. Enable

echo if your PC does not display any characters.

¥ See ÒSet Local EchoÓ on page 38 for more information.

AT response messages do not appear correctly on your PC but

AT commands appear correctly.

¥ If numbers are being returned to the PC instead of messages,

change the message code setting on the CTA 500dm. See

ÒVerbose ControlÓ on page 40 for more information. The

numeric responses and indications are shown in ÒNumeric

CTA 500dm responsesÓ on page 83.

¥ Make sure that your terminal is operating in full duplex mode

rather than half duplex mode.