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telnet to Cognex In-Sight 4001 camera

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  telnet to Cognex In-Sight 4001 camera chris.annin@gmail.com - 2013-02-25 09:02 -0800
    Re: telnet to Cognex In-Sight 4001 camera MRAB <python@mrabarnett.plus.com> - 2013-02-25 17:29 +0000
      Re: telnet to Cognex In-Sight 4001 camera chris.annin@gmail.com - 2013-02-25 11:48 -0800
      Re: telnet to Cognex In-Sight 4001 camera chris.annin@gmail.com - 2013-02-25 11:48 -0800
    Re: telnet to Cognex In-Sight 4001 camera chris.annin@gmail.com - 2013-02-25 17:16 -0800
      Re: telnet to Cognex In-Sight 4001 camera Roy Smith <roy@panix.com> - 2013-02-25 20:44 -0500

#39896 — telnet to Cognex In-Sight 4001 camera

Hello,  ive been struggling with this for a couple weeks now and was hoping someone might be able to help.  I have an older Cognex camera that I need to communicate with via telnet.  I can get a response from the camera when 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:
[code]
>>>import sys
>>>import telnetlib
>>>HOST = "10.31.18.21"
>>>USER = "admin"
>>>tn = telnetlib.Telnet(HOST)
>>>tn.read_until("Login: ")
"Welcome to In-Sight(R) 4001 Session 1\r\nUser:"
>>>tn.write(USER + "\r\n")
>>>tn.read_until("User: ")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Python27\lib\telnetlib.py", line 319,
    return self.read_very_lazy()
  File "C:\Python27\lib\telnetlib.py", line 395,
    raise EOFError, 'telnet connection closed'
EOFError: telnet connection closed
>>>
[\code]

if i do a read_all instead of read_until for user I just get "..." returned.  Im assuming tn.write command isnt working?  any help would be greatly appreciated.

thank you

Chris

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#39899

On 2013-02-25 17:02, chris.annin@gmail.com wrote:
> Hello,  ive been struggling with this for a couple weeks now and was hoping someone might be able to help.  I have an older Cognex camera that I need to communicate with via telnet.  I can get a response from the camera when 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:
> [code]
>>>>import sys
>>>>import telnetlib
>>>>HOST = "10.31.18.21"
>>>>USER = "admin"
>>>>tn = telnetlib.Telnet(HOST)
>>>>tn.read_until("Login: ")
> "Welcome to In-Sight(R) 4001 Session 1\r\nUser:"

The returned string ends with "User:", presumably the prompt to enter
the username, which makes we wonder whether you should be reading until
"User:" instead of until "Login: ".

>>>>tn.write(USER + "\r\n")

Should you be ending that with just "\r" or just "\n" instead? (That
would be equivalent to typing the username and then pressing the Return
key.)

>>>>tn.read_until("User: ")

Haven't you already seen "User: "?

> Traceback (most recent call last):
>    File "<stdin>", line 1, in <module>
>    File "C:\Python27\lib\telnetlib.py", line 319,
>      return self.read_very_lazy()
>    File "C:\Python27\lib\telnetlib.py", line 395,
>      raise EOFError, 'telnet connection closed'
> EOFError: telnet connection closed
>>>>
> [\code]
>
> if i do a read_all instead of read_until for user I just get "..." returned.  Im assuming tn.write command isnt working?  any help would be greatly appreciated.
>

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#39907

On Monday, February 25, 2013 9:29:54 AM UTC-8, MRAB wrote:
> On 2013-02-25 17:02, chris.annin@gmail.com wrote:
> 
> > Hello,  ive been struggling with this for a couple weeks now and was hoping someone might be able to help.  I have an older Cognex camera that I need to communicate with via telnet.  I can get a response from the camera when 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:
> 
> > [code]
> 
> >>>>import sys
> 
> >>>>import telnetlib
> 
> >>>>HOST = "10.31.18.21"
> 
> >>>>USER = "admin"
> 
> >>>>tn = telnetlib.Telnet(HOST)
> 
> >>>>tn.read_until("Login: ")
> 
> > "Welcome to In-Sight(R) 4001 Session 1\r\nUser:"
> 
> 
> 
> The returned string ends with "User:", presumably the prompt to enter
> 
> the username, which makes we wonder whether you should be reading until
> 
> "User:" instead of until "Login: ".
> 
> 
> 
> >>>>tn.write(USER + "\r\n")
> 
> 
> 
> Should you be ending that with just "\r" or just "\n" instead? (That
> 
> would be equivalent to typing the username and then pressing the Return
> 
> key.)
> 
> 
> 
> >>>>tn.read_until("User: ")
> 
> 
> 
> Haven't you already seen "User: "?
> 
> 
> 
> > Traceback (most recent call last):
> 
> >    File "", line 1, in 
> 
> >    File "C:\Python27\lib\telnetlib.py", line 319,
> 
> >      return self.read_very_lazy()
> 
> >    File "C:\Python27\lib\telnetlib.py", line 395,
> 
> >      raise EOFError, 'telnet connection closed'
> 
> > EOFError: telnet connection closed
> 
> >>>>
> 
> > [\code]
> 
> >
> 
> > if i do a read_all instead of read_until for user I just get "..." returned.  Im assuming tn.write command isnt working?  any help would be greatly appreciated.
> 

yea you are right I shouldnt be doing read_until("User: ") I tried read_until("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 “Send Line Ends with Line Feeds” option for it to work.  I thought by using "\r\n" would emulate the same thing?

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#39910

On Monday, February 25, 2013 9:29:54 AM UTC-8, MRAB wrote:
> On 2013-02-25 17:02, chris.annin@gmail.com wrote:
> 
> > Hello,  ive been struggling with this for a couple weeks now and was hoping someone might be able to help.  I have an older Cognex camera that I need to communicate with via telnet.  I can get a response from the camera when 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:
> 
> > [code]
> 
> >>>>import sys
> 
> >>>>import telnetlib
> 
> >>>>HOST = "10.31.18.21"
> 
> >>>>USER = "admin"
> 
> >>>>tn = telnetlib.Telnet(HOST)
> 
> >>>>tn.read_until("Login: ")
> 
> > "Welcome to In-Sight(R) 4001 Session 1\r\nUser:"
> 
> 
> 
> The returned string ends with "User:", presumably the prompt to enter
> 
> the username, which makes we wonder whether you should be reading until
> 
> "User:" instead of until "Login: ".
> 
> 
> 
> >>>>tn.write(USER + "\r\n")
> 
> 
> 
> Should you be ending that with just "\r" or just "\n" instead? (That
> 
> would be equivalent to typing the username and then pressing the Return
> 
> key.)
> 
> 
> 
> >>>>tn.read_until("User: ")
> 
> 
> 
> Haven't you already seen "User: "?
> 
> 
> 
> > Traceback (most recent call last):
> 
> >    File "", line 1, in 
> 
> >    File "C:\Python27\lib\telnetlib.py", line 319,
> 
> >      return self.read_very_lazy()
> 
> >    File "C:\Python27\lib\telnetlib.py", line 395,
> 
> >      raise EOFError, 'telnet connection closed'
> 
> > EOFError: telnet connection closed
> 
> >>>>
> 
> > [\code]
> 
> >
> 
> > if i do a read_all instead of read_until for user I just get "..." returned.  Im assuming tn.write command isnt working?  any help would be greatly appreciated.
> 

yea you are right I shouldnt be doing read_until("User: ") I tried read_until("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 “Send Line Ends with Line Feeds” option for it to work.  I thought by using "\r\n" would emulate the same thing?

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#39919

On Monday, February 25, 2013 9:02:54 AM UTC-8, chris...@gmail.com wrote:
> Hello,  ive been struggling with this for a couple weeks now and was hoping someone might be able to help.  I have an older Cognex camera that I need to communicate with via telnet.  I can get a response from the camera when 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:
> 
> [code]
> 
> >>>import sys
> 
> >>>import telnetlib
> 
> >>>HOST = "10.31.18.21"
> 
> >>>USER = "admin"
> 
> >>>tn = telnetlib.Telnet(HOST)
> 
> >>>tn.read_until("Login: ")
> 
> "Welcome to In-Sight(R) 4001 Session 1\r\nUser:"
> 
> >>>tn.write(USER + "\r\n")
> 
> >>>tn.read_until("User: ")
> 
> Traceback (most recent call last):
> 
>   File "<stdin>", line 1, in <module>
> 
>   File "C:\Python27\lib\telnetlib.py", line 319,
> 
>     return self.read_very_lazy()
> 
>   File "C:\Python27\lib\telnetlib.py", line 395,
> 
>     raise EOFError, 'telnet connection closed'
> 
> EOFError: telnet connection closed
> 
> >>>
> 
> [\code]
> 
> 
> 
> if i do a read_all instead of read_until for user I just get "..." returned.  Im assuming tn.write command isnt working?  any help would be greatly appreciated.
> 
> 
> 
> thank you
> 
> 
> 
> Chris

After much goofing around I figured out that every time I read from this Cognex 4000 series camera the connection either goes dead or disconnects.  If I simply stop trying to read_until or read_all and just write everything it works fine.  here is what worked for me:

import sys
import telnetlib
host = "10.31.18.21"
tn = telnetlib.Telnet(host)
tn.write("admin\r\n") #the user name is admin
tn.write("\r\n") #there is no password - just return - now logged in
tn.write("SO0\r\n") #"SO"=cognex "set online" therefore "SO0" = camera offline
tn.write("LFsomevisionjob.job\r\n") #"LF" = cognex native command "load file"
tn.write("SO1\r\n") #"SO"=cognex "set online" therefore "SO1" = camera online
tn.close()

I doubt anyone has a camera this old they are trying to telnet to in python but if so maybe this thread will help someone out.

thanks again for all your replies - really appreciate you guys helping me out.
Chris

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#39920

In article <71787193-b4aa-438f-a8f1-058873346e27@googlegroups.com>,
 chris.annin@gmail.com wrote:

> On Monday, February 25, 2013 9:02:54 AM UTC-8, chris...@gmail.com wrote:
> > Hello,  ive been struggling with this for a couple weeks now and was hoping 
> > someone might be able to help.  I have an older Cognex camera that I need 
> > to communicate with via telnet.  I can get a response from the camera when 
> > 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.

Two suggestions I can make.

One is to use the command-line telnet utility to talk to the camera.  
Verify that you can at least make a connection and authenticate that way.

Second, use a packet sniffer to watch the actual traffic going back and 
forth to the camera.  On a Unix box, I would do:

$ tcpdump -s 0 -A host 10.31.18.21

but it looks like you're on windows, so you'll want to use Wireshark 
(http://www.wireshark.org/) instead of tcpdump.  If you're not familiar 
with TCP protocol details, you'll want to read up on it so you can 
properly interpret what tcpdump or Wireshark is telling you.

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