Ajay,
I don't have your external instrument handy, but I just tried a couple of tests using the ITK Telnet VIs on LabVIEW 5.1 and 6.1:
1. I wrote a test 5.1 VI that uses Telnet Play Script as a subVI, and I wrote a listener VI using the regular TCP/IP functions. The listener reported the same bytes coming across regardless whether I sent them from the test VI under LabVIEW 5.1 or 6.1.
2. I wrote a test VI (attached) that opened a local telnet session to Win2K Telnet Server and sent a series of commands (username, password, dir, exit) using Telnet Play Script. Again, I got consistent behavior under 5.1 and 6.1; the commands executed successfully on the server.
I did notice some unprintable text prefixed/suffixed around the response strings from the s
erver, but I saw the same text under 5.1 and 6.1, and it didn't affect my script. My feeling is that the extra text has something to do with terminal emulation. As long as I got a reliable prompt string at the end of it, all was well.
Maybe you can do a sanity check with my test VI if you have access to another telnet server besides your instrument. Is it possible that something other than the telnet part of things might have been affected by your move from 5.1 to 6.1 and is the true root cause here?
If you really do narrow things down to the telnet part of things, you might want to unit-test portions of the telnet VI code until you isolate the problem. Maybe the Read Mode on the read VI or the Write Mode on the write VI has something to do with the misbehavior.
Hope it helps,
John Lum
National Instruments
