ZyXEL Communications U-336R/RE manual Trouble Shooting, AT Command Set Problems

∙Resent Expiration

∙Protocol Error

∙Break Timeout

∙DTR Dropped

∙Carrier Lost 1 (No handshaking response)

∙Carrier Lost 2 (Remote hang-up, busy tone heard)

Trouble Shooting

Your modem is designed to provide years of ultra high speed satisfaction. In the unlikely event you encounter problems using your modem, the tips in this section will help you to identify and resolve them. Most modem problems are a result of incorrect cabling or settings within your communications or fax software. This section provides a list of more common problems that you may encounter, followed by likely solutions.

AT Command Set Problems

Problem

Your modem does not respond to AT commands.

Solutions

1.Make sure the DTR LED is ON. If it is OFF, make sure your communications software is using the same COM port as your modem.

2.Check to see that your modem’s COM port is not already assigned to another installed serial device, such as a mouse or laser printer.

126 Diagnostics & Troubleshooting