Working with VISA resources in Labview 6

Question

I am having difficulties programming through VISA in Labview 6.0.2. I have installed MAX 3.2, and have configured my two devices going through USB:
1) an Agilent 82357A USBtoGPIB adapter connected with an Agilent 53131A Universal Counter
2) a USBtoRS422 converter registered as serial COM4 connected with a Rainin Peristaltic pump
I can open communication with both devices from within MAX, and send/receive data with no problem.
When I try to program in Labview 6, I cannot communicate with either VISA device, even though I am using VISA instrument IO vi's with the configured VISA resource name from MAX. I'm not sure what I'm doing wrong.
Is there an incompatability between MAX 3.2 and Labview 6.0.2, or have I configured something wrong?
Thank you for the assistance.

Answer 1

Hello,
I think we can defeat the problem with Device 1 fairly quickly. If you have established that you can communicate with the device in MAX, I think we simply have a small programmatic change to make in LabVIEW. I am interested in having you attempt using the VI I have attached, which allows you to specify the bytes you would like to send in an array, and then simply sends the corresponding the string of ascii characters (the characters corresponding to the values in the array); this way we can be sure to send exactly what we would like. The following link has an ascii table in it, which you can use as a reference when putting the values into the array: (where the first byte specified will be the first character in the string)
http://www.ni.com/pdf/manuals/371253a.pdf
Simply change the VISA resource name to reflect your device and give it a try.
As for Device 2, let's try using the same VI (attached) and write a command which the device is known to understand. A simply query would be approprite, where you can write using the attached VI, and then read using another VI which literally only has a VISA Read function in it (and a resource control or constant connected with your resource specified).
One thing to verify before reposting is whether the devices you have use EOS (end of string) and/or EOI (end or identify) termination of GPIB operations. For EOS, a character is sought by the listener to indicate the end of a transmitted string, such as a linefeed or carriage return (or both). EOI termination is defined by the talker asserting the EOI line when the last byte to be transmitted is sent; the listener knows it has received the last byte of that transmission.
Definitely repost; it is likely that we are only few programmatic changes and perhaps a spec check (for the devices) away from dependable communication
Thank you,
JLS
Best,
JLS
Sixclear
Attachments:
WriteByteArray.vi ‏14 KB