Fluke PPC4 GPIB timeout (time-out)

[JohnBoy]

I have a problem with a brand-new Fluke PPC4 on GPIB.  Usually, the unit works without error.  It works with MAX perfectly normally.  My LabVIEW 7.1 program (operating under Windows 2000), which we have used for several years, works well for quite a while, but occasionally encounters a GPIB timeout.  This may happen after a few seconds of operation, or after 40 or so minutes of operation.  However, the time-out (which I have captured with a LabVIEW probe) seems always to happen when a PRR? command has been sent to the unit (via a VISA Write in a Fluke-written driver).  Although that operation does not time-out, the VISA Read that follows does.  That VISA Read is expecting to read the pressure that was returned as a result of the VISA Write.  After reading various suggestions on this forum, I've added a delay between the Write and the Read.  I've tried both 100 ms and 200 ms, but neither helped at all.  I still have the same very intermittent time-out fault.  NI-spy captures the error, but as far as I can see, doesn't reveal anything.  A typical capture reads:

viRead (0x00218028,0x140FBCF4, 255, 0)

Processs ID: 0x00000634   Thread ID: 0x00000630

Start Time: 09:33:18.212   Call Duration: 00:00:04.625

Status: 0xBFFF0015 (VI_ERROR_TMO)

Can anybody help, please?

[Dennis_Knutson]

Are you sending any configuration commands to the instrument before doing the query? It's possible that the instrument is simply to busy to process the measurement request and a delay before the write is necessary. There are methods, such as using the OPC? (operation complete) query to see if the instrument is busy.You could also do an ERR? query before the write to see if the instrument is in an error state. This would also prevent a measurement.

You haven't posted your code for anyone to look at to see if there is something wrong there and that is something you should do. I would also recomend contacting Fluke sine, as you said, it is their driver.

[JohnBoy]

Thanks for your suggestions, Dennis.  I've tried many things and am now working with Fluke to try to resolve the problems.  A similar timeout problem also happens with the Fluke PPC4 using RS-232.

[JohnBoy]

After many, many months, Fluke appear to have found this to be caused by the PPC4 being connected to an external reference baometer (a Fluke RPM4) whereas usually an internal reference is used.  It seems more time is being taken with comms between the two, resulting in occaisional timeouts to the LabVIEW application.  Fluke are rumoured to be working on a new firmware release to fix the problem.