Subj : USR 5686 no reply at AT command
To   : rmurray
From : Fzf
Date : Wed Aug 21 2024 08:07 pm

  Re: USR 5686 no reply at AT command
  By: rmurray to All on Wed Aug 21 2024 11:02 pm

 rm> The issue is that it doesn't respond to any AT commands sent to it.

Try issuing the command:

AT&R1<ENTER>

Then try a plain AT<ENTER> and then ATI5<ENTER>.

 rm> I've tested
 rm> them on several serial ports across multiple computers, including the
 rm> built-in ports on the motherboard and special RS232 serial cards.

By any chance are you using the same serial cable (and maybe adapters) when doing each of these tests?  The AT&R1 command above will temporarily disable RTS handshaking on the modem side.  If you get a response after issuing it, this will indicate the hardware handshaking isn't configured correctly.
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