LV 2010 GPIB issues

[ds_1]

Hi All,

         Since moving to Labview 2010 we've been encountering a number of issues controlling GPIB instruments with GPIB/VISA. One of these has been the subject of a collegues prvious post involving a DATRON DC calibrator. As this is a rather old instrument some of the code we were using was dated (using GPIB vi's) and we have now rewritten using VISA but the problem still exists, infact I think we can safely eliminate the code from the issue altogether!

In the case where the DATRON is present on the Bus:

Symptoms:

Writes/Reads to other instruments on the Bus take ages (20-30 seconds) to respond, e.g. PSU's DMM's

DMM's  (Agilent 3458's) sometimes report "syntax errors" where they shouldn't (i.e. when in a loop reading back measurements)

This occurs as soon as the DATRON is powered on. (i.e. not a single command has been issued to it)

This occurs with different DATRON instruments (even models) at different lab set ups, even different lab locations using different code.) 

the second the DATRON is powered off, READ/WRITES again occur at normal speeds

Work around:

At 2 different locations where this issue arose, engineers found the only way around this was to take the DATRON of the BUS with the other instruments. This was done by using a GPIB <-> USB convertor for the DATRON to use it. This is not ideal.

This issue does not occur on older labview versions. These instruments have been in use for many many years without these issues.

I've used NI-SPY on the bus and cannot see any rouge messages or garbage on the bus.

My feeling is that as the DATRON is an old instrument, perhaps it isn't exactly IEEE 488 complient and perhaps these instruments are no longer strictly supported by the NI GPIB cards/drivers? 

On other instruments I am now starting to also see some more erros occurring that are a little unusual (occasional errors using the Instrument Drivers VI downloaded from NI, that has never appearded before)

I'm just wondering has there been a significant change to GPIB under LV 2010 that might explain some of this?

Thanks

ds1 

[Albert.Geven]

Did you specify the bus speed in MAX for the gpib bus? make it 2micro seconds

And maybe you also should disable autopolling.

These things can help out especially for older instruments

[ds_1]

Hi,

     Thanks for your resonse. When I look at all GPIB settings in MAX they are all greyed out. How can these be changed? It says "can only be changed by Administrator" I should have full access to all setting on this PC.

      Also, have the defaults here changed from previous versions? As I've never had to modify these for LV 7.1, 8.0, 8.5,.8.6 where older instruments worked fine.

[ds_1]

Hi ,

       I found how to change settings. (Had to run MAX as Admin to edit) I made the changes suggested and put the instrument back on the bus, and immediately this slowed things down again so this made no difference.

[Albert.Geven]

I did not notice any difference between the LabVIEW versions.

coincidences happen! did you check the cabling, and were all other intsruments (at least 2/3) switched on?

[ds_1]

This issue has been seen on 3 individual PC/Lab set ups. And been reported seperately by 3 engineers.  (1 in a different geographical location) The only common thing between the 3 was the Labview 2010 upgrade. Cabling etc was ruled out of each set up. We have reports that this "gets slower over time" In that the GPIB seems to be slowing down as the system is in use for some time, but this is hard to quantify and test.

[Albert.Geven]

I I suspect one thing than it is the visa version more than the LabVIEW version.

Did you try the latest visa?