Trouble Shooting; At Command Set Problems - ZyXEL Communications U-336E User Manual

FRN Request (FR)
The count of the local modem's requests to change the rate.
Block Retransmitted (BR)
The count of the blocks retransmitted (bad reception on the remote
modem).
FCS (Frame Check Sum) Errors (FE)
The count of the FCS errors received (block errors) (bad reception
on the local modem).

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.
Problem
Your modem fails to execute AT commands.
Diagnostics & Troubleshooting 113