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Newsgroups: comp.lang.python
Date: Mon, 25 Feb 2013 11:48:46 -0800 (PST)
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Subject: Re: telnet to Cognex In-Sight 4001 camera
From: chris.annin@gmail.com
To: comp.lang.python@googlegroups.com
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On Monday, February 25, 2013 9:29:54 AM UTC-8, MRAB wrote:
> On 2013-02-25 17:02, chris.annin@gmail.com wrote:
>=20
> > Hello,  ive been struggling with this for a couple weeks now and was ho=
ping someone might be able to help.  I have an older Cognex camera that I n=
eed to communicate with via telnet.  I can get a response from the camera w=
hen I initiate a telnet session but I dont seem to get any response when I =
write the user name to the camera -  I havnt been able to get any response =
writing anything. Im using python 2.7 and windows xp.  here is the code:
>=20
> > [code]
>=20
> >>>>import sys
>=20
> >>>>import telnetlib
>=20
> >>>>HOST =3D "10.31.18.21"
>=20
> >>>>USER =3D "admin"
>=20
> >>>>tn =3D telnetlib.Telnet(HOST)
>=20
> >>>>tn.read_until("Login: ")
>=20
> > "Welcome to In-Sight(R) 4001 Session 1\r\nUser:"
>=20
>=20
>=20
> The returned string ends with "User:", presumably the prompt to enter
>=20
> the username, which makes we wonder whether you should be reading until
>=20
> "User:" instead of until "Login: ".
>=20
>=20
>=20
> >>>>tn.write(USER + "\r\n")
>=20
>=20
>=20
> Should you be ending that with just "\r" or just "\n" instead? (That
>=20
> would be equivalent to typing the username and then pressing the Return
>=20
> key.)
>=20
>=20
>=20
> >>>>tn.read_until("User: ")
>=20
>=20
>=20
> Haven't you already seen "User: "?
>=20
>=20
>=20
> > Traceback (most recent call last):
>=20
> >    File "", line 1, in=20
>=20
> >    File "C:\Python27\lib\telnetlib.py", line 319,
>=20
> >      return self.read_very_lazy()
>=20
> >    File "C:\Python27\lib\telnetlib.py", line 395,
>=20
> >      raise EOFError, 'telnet connection closed'
>=20
> > EOFError: telnet connection closed
>=20
> >>>>
>=20
> > [\code]
>=20
> >
>=20
> > if i do a read_all instead of read_until for user I just get "..." retu=
rned.  Im assuming tn.write command isnt working?  any help would be greatl=
y appreciated.
>=20

yea you are right I shouldnt be doing read_until("User: ") I tried read_unt=
il("Password: ") instead but didnt make any difference.  If I use read_all(=
) I just get ,,, like there is nothing to read.  in hyperterminal I had to =
set the =93Send Line Ends with Line Feeds=94 option for it to work.  I thou=
ght by using "\r\n" would emulate the same thing?