Telnet using TCP vi's

Question

Labview 7.1
Windows XP Pro / DOS
Using the TCP vi's I am able to successfully talk back and forth on port 23 to the labview basic telnet server example found on the ni website (local host)
I am also able to talk to this labview telnet server example using the DOS command interface . Everything seemed rosey until I tried using the same TCP vi's to look at a real remote system. The DOS command interface works great to access the remote system using Telnet. I get the correct return prompt of
login:
When I try to access the remote system with the TCP vi's I get:
 ÿý ÿý ÿý#ÿý'ÿý$
This return prompt is consistant. Same thing every time. I also found a TCP example on the ni website, and I get exactly the same response. I am reasonably sure the connection is being made based on other factors, just getting junk back. ????
I am using TCP write and TCP read and TCP open connection
gtb

Answer 1

Hi gtb,
For future reference, this message is attached to the Telnet Server example: "National Instruments has not reviewed this program, does not support
this program, and does not guarantee its quality in any way." There's no way to tell if this program will work with your application, so I would recommend using it as a reference point and not a standard.
Stil, I found these two previous posts which discuss this problem:
garbled response when TCP connect is used with telnet
   http://forums.ni.com/ni/board/message?board.id=170&message.id=137137&requireLogin=False
Re: How do I establish a telnet session with unit under test?
   http://forums.ni.com/ni/board/message?board.id=170&message.id=112886&query.id=0#M112886
As discussed in the 2nd post, "If you want to do telnet using plain TCP, you need to do everything yourself, including the telnet options negotiation."
It appears more efficient to use NI's Telnet VIs, but the 2nd post gives you the necessary information for writing telnet using plain TCP. Cheers.
Michael K.
| Michael K | Project Manager | LabVIEW R&D | National Instruments |