[newbie] trying socket as a replacement for nc

[Jean Dubois]

Op maandag 16 december 2013 20:21:15 UTC+1 schreef Jean-Michel Pichavant:
> ----- Original Message -----
> > On Tue, Dec 17, 2013 at 5:26 AM, Jean Dubois
> > <jeandubois314 at gmail.com> wrote:
> > >> Try something simple first:
> > >> import telnetlib
> > >> host = '10.128.59.63'
> > >> port = 7000
> > >> t = Telnet(host, port)
> > >> def flush()
> > >>   t.read_very_eager()
> > >> def sendCmd(cmd)
> > >>   t.write('%s\n' % cmd)
> > >>   return flush()
> > >> flush()
> > >> print sendCmd('*IDN?')
> > >> print sendCmd('*OPC?')
> > > Still no success:
> > > jean at mantec:~$ ./test.py
> > >   File "./test.py", line 7
> > >     def flush()
> > >               ^
> > > SyntaxError: invalid syntax
> > >
> > >
> > > Tried it both with python2 and python3, same error...
> > 
> > Folks, the OP isn't an expert. Please test your scripts before
> > posting!
> > 
> > I don't have everything I need to test this fully, but here's a
> > variant of the above that's at least syntactically correct:
> > 
> > from telnetlib import *
> > host = '10.128.59.63'
> > port = 7000
> > t = Telnet(host, port)
> > def flush():
> >   t.read_very_eager()
> > def sendCmd(cmd):
> >   t.write('%s\n' % cmd)
> >   return flush()
> > flush()
> > print sendCmd('*IDN?')
> > print sendCmd('*OPC?')
> > 
> > It's written for Python 2, so use that interpreter.
> > 
> > ChrisA
> It was done on purpose, for educational purpose... :) 
> My bad, however I should point that learning the very basic of a language by implementing a low level equipment remote protocol is rather ambitious.
> By experience I know that you are annoyed by a crapload of nasty details without even caring about the python syntax, including:
>   * LF/CR sequence
>   * Inconsistent  answer pattern, depending on the equipment vendor
>   * broken netcode that can block the remote server
>   * timeouts
>   * poor equipment feedback
> I still wish Jean a great success :)
I'm a newbie in Python programming that is very much true, and contrary to what you seem to suggest I did my homework: I succeeded
already in writing a Python-script which communicates directly over rs232 with the same device which I now am trying to connect to via a rs232-ethernet adapter.
So I thought it would be simply a matter of communicating the same commands as I did before.
Here are some parts of my code:
serkeith = serial.Serial('/dev/ttyUSB0', 9600, 8, timeout=5, xonxoff=1)
serkeith.write("*RST" + "\n")
#turn off concurrent functions
serkeith.write(":SENS:FUNC:CONC OFF" + "\n")
#current source function
serkeith.write(":SOUR:FUNC CURR" + "\n")
#volt sense function
serkeith.write(":SENS:FUNC 'VOLT:DC'" + "\n")
#105V compliance
#serkeith.write(":SENS:VOLT:PROT 105" + "\n")
compliancestring=':SENS:VOLT:PROT '+str(compliancevalue) + '\n'
serkeith.write(compliancestring)
.
.
keithleymeasurement=serkeith.readline().split(',')

Also I got it working with nc and telnet, I just don't know how to accomplish this using python.
Tomorrow I'll look further at some a the more recent suggestions

kind regards,
jean