USB<->RS232 VISA Error under Mac OS X

[JILee]

I'm using a IOGear USB<->RS232 adapter (GUC232A) to get a serial port on a Mac running OS X. The serial port seems to work fine in LabVIEW 7 *most* of the time. Sometimes I get a VISA error when performing a VISA write: 0xBFFF003E and the "Explain Error" text is "Could not perform operation because of an I/O error". I can only get back in business by closing the VISA port and re-opening it.

"...because of an I/O Error" doesn't really give me enough information to troubleshoot this problem. Is it a VISA driver thing? Is the the USB<->RS232 thing? Is it a problem with my code? What, specifically, is the I/O error? If this is simply a "catch-all" error code, can you at least figure out what the problem *isn't* caused by?


More info - the error doesn't occur in my Windows version of code, only the Mac version, and I used the same USB<->RS232 dongle.

JIL

[BeckyB]

Hello JIL -

What version of VISA do you have installed on each PC? The current versions for each operating system can be found here.

Have you reviewed the document Using NI-VISA 3.0 to Control Your USB Device? It is a very informative document that may help.

If neither of these suggestions work, please let me know. This appears to be an unknown problem and I can file a corrective action request with our R&D department so it can be further investigated.

Have a great day!

Becky B.
Applications Engineer
National In
struments

[JILee]

Hi BeckyB,

Thanks for replying to my post!

I'm using NI-VISA 3.0 on the Mac; let's just worry about the Mac since the PC version works fine.

I guess I wasn't clear in my post; our device is a serial device, not a USB device. We are using a USB<->RS232 converter (from IOGear) on the Mac to create a serial port on the Mac (since Macs don't come with one). Since our device appears to LabVIEW 7 as a serial port, the "Using NI-VISA 3.0 to Control your USB device" isn't germane to this problem.

JIL

[Koninika]

Hi Jil,
What probably is happening is that your instrument is not in a state to accept commands. Try running an example VI from the help-> find examples called labview<->serial.vi and see if you observe the same behavior. If you do not see the error, then we know that the problem does lie in your code. If not, then we have to start troubleshooting the problem from a hardware perspective.
Email me back incase you have any other questions.
Good luck and have a great day!
Koninika
National Instruments.

[Andy Toth]

Jil,

I have the same problem at Keithley. I am running NI-VISA through a USB-232 adapter. Issue is that I am having timing errors. I am unsure if it is NI-VISA Ver. or the Adapter. What I am trying to do is have OS create a Serial COM and have NI-VISA pick it up. Did you have any success?