Continuous monitor for new GPIB messages

[j_osh_o]

I have an automated wafer prober that periodically sends GPIB messages that need to be parsed and acted on.  There can be as much as a minute between messages, or as little as a few millisenconds.  I am using VISA Read STB to check the status byte every 10 milliseconds.  If I see the ATN bit asserted, then I perform a VISA Read and parse the message.  I suppose I could use a VISA Read with infinite timout, but I am worried that this will tie up the thread if I need to shutdown quickly.  Is there a better way to do this other than repeatedly polling the STB?

[smercurio_fc]

What programming platform are you using? Have you tried using VISA Events?

[j_osh_o]

I am using LabVIEW 7.0 on Solaris.  I have not heard of VISA events. 

[smercurio_fc]

You can enable events and then wait on events. LabVIEW 7.1 has these, but I'm not sure about 7.0. If they're available there's an example that uses these to detect a break event on a serial connection. You could try to make use of the GPIB Talk and Listen events.

[j_osh_o]

I looked into VISA events, and it seems this is not the right solution for me.  The automated prober I am communicating with sends unsolicited commands that need to be parsed and acted on.  While I am listening for these commands, I need the GPIB bus available for writes in case I need to abort the actions of the prober.  The wait for VISA events seems to tie up the GPIB bus preventing any writes.  There is no way that I can see to abort the wait vi once it is started, so this really does not solve my problem.

My original message shows I was confused between the "interface status byte" and the "device status byte".  Using VISA Read STB vi, the "device status byte" can be read.  Bit 4 of the device status byte is Message Available (MAV).  By polling this bit, I can check if there are any unsolicited messages pending from the prober.

Polling is not the most elegant solution, but from the information I have been able to dig up it seems the only one.

[smercurio_fc]

Moved.