RS-485 Garbled using VISA (not HyperTerm)

[Havarti]

I have a RS485 UART that echoes data back.  It's baud rate is 38400, everything else is the usual default settings.  When I type into a Hyperterm console it echoes back just exactly what I type in.  However, when using LabVIEW and VISA subvis to send a small message and read from the port, the read text is SLIGHTLY garbled.  Maybe 1 out of ever 4 or 5 characters is missing or changed(usually missing.)

I have check the settings a ridiculous amount of times so I am quite confident that the Hyperterm and VISA settings are identical.  Also, nothing is changing physically between the two tests, so it seems that there is something going on with the software.  I thought that maybe it was because a whole message was being sent before the read, so I tried sending one character at a time (like what would happen when typing in a hyperterm) but I still got garbled results.

Any ideas?  Thanks.

[Swathi B]

Hi Havarti,

I'm assuming you are seeing the same behavior through VISA test panels as with LabVIEW, is that correct? If so, here is a KnowledgeBase that covers some of the typical issues with regard to differences between the two environments. I know you had mentioned attempting to send a character at a time, but it may be worthwhile to also test the VISA drop in replacements (linked to the document).