Addressing the modem via pyserial

[Doru-Catalin Togea]

Hi!

I asked previously how to address the COM port from Python and I was
directed to pyserial. It is very elegant and I guess it works very well.

However, it seems that what I try to do is more complicated than I first
thought. I want to make my modem place a call using the number '1234'. The
modem is connected to COM3 on my computer. So I tried the following:

-------------------------------
import serial

ser = serial.Serial(2) # COM3
ser.timeout = 2 # otherwise the read(2) which follows blocks for ever
ser.write("atdt1234")
reply = ser.read(2)
print reply
ser.close()
print "ok"
-------------------------------

In the HyperTerminal which comes with Win XP Pro, I can set up a
connection to COM3 and there type the 'atdt1234' command. It works (I get
a call since I have the modem connected to a device with a phone on it).

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

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.

Any ideas?

Thanks,
Catalin

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[Fredrik Lundh]

Doru-Catalin Togea wrote:

In the HyperTerminal which comes with Win XP Pro, I can set up a
connection to COM3 and there type the 'atdt1234' command. It works (I get
a call since I have the modem connected to a device with a phone on it).
even without pressing enter?
My question is actually: will an at-command like 'atdt1234' translate to
ser.write('atdt1234')?

try

ser.write('atdt1234\r\n')

or just

ser.write('atdt1234\n')

</F>

[Roel Schroeven]

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