Addressing the modem via pyserial

Roel Schroeven rschroev_nospam_ml at
Wed Jan 18 22:56:47 CET 2006

Doru-Catalin Togea schreef:
> My question is actually: will an at-command like 'atdt1234' translate to 
> ser.write('atdt1234')?

You'll have to include the end-of-line; I guess 'atdt1234\n' should 
work, otherwise you can try 'atdt1234\r\n' or 'atdt1234\r'.

Also, don't forget that you have to set the modem into command mode if 
it was not already (using '+++' and a pause before and/or after that 
IIRC), but I guess that's not the problem in this case.

> Secondly, a modem question: I have found a lot of web pages about 
> at-commands listing the hayes command set. Still many of them do not 
> seem to work on two different modems I have tried. Like '&$' should 
> display an overview of the commands supported by the modem. Ii tried 
> this in the HyperTerminal where I can place the above mentioned call, 
> and I get 'ERROR'. I also get 'ERROR' for most other commands I try.

Unfortunately the hayes command set is not a well-defined standard 
supported by all modems. There are almost as many variations as there 
are modems. In the good old days the user manual that came with the 
modem had an overview of the available commands for that modem.

If I have been able to see further, it was only because I stood
on the shoulders of giants.  -- Isaac Newton

Roel Schroeven

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