Using USB device with Virtual Com port

[Chris_R.]

Hi Matt,

Since the write seems to be recognized successfully by VISA (according to Portmon), you may want to decrease the timeout to a small number and then ignore the errors.  This may prevent the "1" from being sent and if your instrument received the command, it may have a chance to respond to it.  Without the "1" confusing things, it may work properly with the command already sent.  There is not much else to suggest since VISA is not typically supported with virtual COM ports.  Let me know if you have any other questions or if you discover anything else in your troubleshooting.

Chris R.

[MattEE]

A follow up. Labview 6.1 serial compatibility VIs do NOT use VISA. That is why my device worked on a 6.1 system. Starting at 7.0 NI changed the VIs to use VISA.  My solution is to use LabView 6.1 because it actually works properly.