GPIB problem

[ab359]

I am controlling HP8672A with Labview standard GPIB write routine.  When I turn on the HP and try to controll it, it does not work (time out message).  I then go to MAX and to "communicate with device" I jut open and close this window, without actually communicating with the device and it now works fine.  Whe I turn OFF/ON back the HP, I have to repeat this procedure.  What is the source of thsi problem?

Aharon

[Brian F.]

Hello.

Thank you for posting to the NI Discussion Forums. 

When you click on the communicate with device and close the window, 3 commands are completed on the GPIB bus.  I found this by launching NI Spy.  The 3 commands are ibdev, ibclr, ibonl.  These 3 commands have the following high level description in the 488.2 help. 

ibdev: Open and initialize a device descriptor.

ibclr: Clear a specific device.

ibonl: Place the device or interface online or offline.

For some reason, these 3 commands are allowing your program to work successfully after a power cycle. 

I am interested to see a spy capture of your GPIB program as well as your LabVIEW code, which may help with the troubleshooting process.  Can you provide these files?

Brian F
Applications Engineer
National Instruments

[ab359]

Thanks for your reply.  What those commands mean?  How can I use Labview to transmit thos commands and thus avoid this procedure?

About the Labview code, I am using teh example Labview<> GPIB vi and just writing simple string to teh device.  I attach teh spy file when the system is just turned on.

Thanks

Bye

Aharon

[Brian F.]

The error that is being thrown is an EABO error:

"EABO Error Code

EABO indicates that an I/O operation has been canceled, usually due to a timeout condition. Other causes are calling ibstop or receiving the Device Clear message from the CIC while performing an I/O operation. Frequently, the I/O is not progressing (the Listener is not continuing to handshake or the Talker has stopped talking), or the byte count in the call which timed out was more than the other device was expecting.

Solutions

Use the correct byte count in input calls or have the Talker use the END message to signify the end of the transfer.

Lengthen the timeout period for the I/O operation using ibtmo.

Make sure that you have configured your device to send data before you request data."

In terms of information about the 3 commands I listed, I would recommend opening the 488.2 Help File and searching for the commands.  This help document can be found at start>>programs>>National Instruments>>NI-488.2>>NI-488.2 Help. 

Brian F
Applications Engineer
National Instruments

[ab359]

Thanks again.

In Labview teh solution was to add GPIB Misc vi with sic command before talking to the device.

Bye

Aharon