Monitoring GPIB NDAC state in labview?

[kniffing]

I have an old Klinger motor controller I'm trying to control with labview. I'm able to send commands to it using a GPIB-USB-HS and the labview Instrument I/O Assistant but I also need to find out when the motor controller has finished executing a command.

When the contoller is moving the motor, the NDAC and NRFD lines are in the true state. Both lines go to the false state when the motion is complete. Is there a way to monitor the state of the NDAC and/or NRFD handshake lines in labview?

Thanks!

[pflores]

Hello kniffing,

The USB controller you have does not have this ability. Our GPIB Analyzer products do have this ability. Unfortunately, they are not available in USB form factor, only in PCI and PCIe.

These products will give you the ability to monitor all the data and control lines of the GPIB bus in real time.

I hope this helps.

[Steven_T]

Hello Kniffing,

This instrument's behavior seems strange, but I'll write about that later.  NI-488.2 has a C language interface function called iblines that will give you the current state of the GPIB hardware lines.  However this function is not exported into LabVIEW.

If this instrument keeps the NDAC line in a certain state while processing a command, I believe it would be an NDAC hold-off.  One way to see if the hold-off was still in effect is to try to send more data to the instrument.  If the write succeeds, then you know that the instrument has finished.  If the write returns an EABO (basically a timeout) then the instrument is still executing the command.

NI-488.2 in LabVIEW doesn't give you direct access to the lines, but from doing operations on the bus, you should be able to see the state of the lines.

I hope this helps,

Steven T.