How can I fix consistent TCP timeout and make data flow simpler?

[Panthera395]

Hi!
I'm acquiring data from a Scanivalve Digital Scanning Array through a TCP/IP connection. I'm having problems with the connection timing out regularly. It will run fine if you take data several times in a row, but if the VI sits for several minutes (while looking at previous data runs or adjusting test setup) the connection will timeout the next time you try to take data. The subVIs (reading the tcp connection, processing the data pakcet, etc) were provided by the manufacturer several years ago. The midlevel VI were written by another engineer, and I adapted them to run with the top level VI that I needed for this test. The data flow in the VIs are convoluted and while I can follow the ones t
hat I wrote, I'm not sure how to troubleshoot the others.

I posted a question on an unrelated problem and the responses mentioned that race conditions were going to be a problem b/c of all of the global variables.

Please be patient with my lack of knowledge in some areas. Any help would be appreciated.

Thanks so much!
-Sarah

Engineering intern
Techsburg, Inc.

[KileenC]

TCP connections can time out if there is no communication occuring for the specified timout amount of time. There is an example that will automatically have the client reconnect to the server when timeout occurs.

[Panthera395]

If the client automatically reconnects, will that interrupt the time history of the data sent? I have been getting error 56 and the length of timeout is set by the user. The DSA does not take explicit time history data, so I am dependent on the sequence of data points to correlate it with the DAQ data that runs parallel. According the DSA settings, it should read the data packets into an internal queue and stop taking data when the desired number of samples is reached, but leave the data in the queue for the client to access (if I am understanding the literature correctly).

Thanks so much!

[KileenC]

I'm not positive about the best solution in this situation, but there is lots of information available regarding error 56 when using TCP/IP communication.

You might find some of these useful:
Error 56 Occurred at TCP Open: Windows XP Fails as TCP/IP Server with LabVIEW 6.1.

Error 56 Occurs When Using TCP Listen.vi

TCP/IP Error Codes and Related Time-out Issues in LabVIEW