Instrument Control (GPIB, Serial, VISA, IVI)

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viGPIBCOntrolREN from NI_VISA 2.6

While communicate to a HP8720 device using NI-visa Interactive control 2.6, and using viGpibControlREN to set the device to REMOTE, the front panel 'local' key was disabled. It seems that the device is in a local lockout state. I used the mode 'VI_GPIB_REN_ASSERT_ADDRESS', and it sends the following gpib command across the IEEE bus, LLO 11, and UNL 3F. I then tried to press the 'LOCAL' button from the front panel and it didn;t responsed. I then remove the IEEE cable, and the front panel responsed.

Is there something wrong with the VI_GPIB_REN_ASSERT_ADDRESS mode?

Anybody encountered the same problem?
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Hello,

I just tried this on a machine with VISA 3.01 on it, and both VI_GPIB_REN_ASSERT_ADDRESS and VI_GPIB_REN_ASSERT behaved as they should've. Neither one sent the LLO command. This may have been fixed in a version of VISA post-2.6. I was using VISA Interactive Control from Measurement and Automation to perform these tests. Upgrade to the latest version of VISA and see if the problem still occurs: http://digital.ni.com/softlib.nsf/websearch/C136D5E8B4D8E77886256D6B005A4EB5?opendocument&node=132060_US

Scott B.
Applications Engineer
National Instruments
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Would you be able to test it using visa 2.6.0 and see if the LLO GPIB command had been sent?

My configuration right now is NI 488.2 V1.7, VISA V2.6,
MAX 2.2.03, and VXI 3.2. I am not sure if I install VISA 3.0.1 and then try to uninstall it to put v2.6 back on the system will have any other impact with the other drivers.

If it is a known problem with the visa 2.6, then we have to think of something or upgrade our existing configuration if we can.

Thanks...
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Hello,

I setup a machine with NI 488.2 v1.7 and VISA 2.6. I am using a PCI-GPIB board. Hooking up a GPIB+ Analyzer board, I observed communication between the test machine and the instrument. Setting VI_ATTR_REN_ASSERT simply set the REN line to asserted, and DEASSERT would deassert the REN line. Only the specific commands to lock out the local front panel sent the LLO data byte over the GPIB.

Are you sure that you are getting the LLO command across the data bus, or is it possible that the HP instrument will automatically do a local lockout when REN is asserted?

Hope this helps.

Scott B.
Applications Engineer
National Instruments
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Scott,
The VISA version we had was 2.5.2. which had the problem.
I loaded the VISA 3.0.1 version. I opened a session with the device using VISA interactive control and execute the ‘viGPIBControlREN’ with mode parameter set to VI_GPIB_REN_ASSERT_ADDRESS, it did not send the ‘LLO’ across the bus this time. And I was unable to press any front panel button until I press the ‘local’ key on the front panel. It works accordingly at this point. ( Now the device is in local mode since I press the ‘local’ button)

However, there seems to be another problem. If I re-send the viGPIBControlREN command with the mode = VI_GPIB_REN_ASSERT_ADDRESS to reset the device to ‘REMOTE’ mode, it se
ems that it does not work. The device still let me press any front panel keys just like it is in the local mode. It seems that the viGPIBControlREN command did not work after I press the front panel ‘local’ key.

Do you have any idea about this?
Thanks...Dora
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Dora,

VI_GPIB_REN_ASSERT_ADDRESS and also VI_GPIB_REN_ASSERT will assert the REN line. Even after you press "local" on your instrument, the REN line is still asserted. Your instrument probably ignores this line-state since you pressed the 'Local' key, but it still exists and REN is still asserted. Your instrument may go back into local mode if it is deasserted then reasserted, but that is up to the instrument itself. Hope this helps.

Scott B.
Applications Engineer
National Instruments
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