GPIB-USB-HS works selectively

[Filou2]

Situation

-an old HP3962A works nicely using a PCI-GPIB card on a PC. Labiew code.

- a K2000 dvm works nicely using a GPIB-USB-HS hub, on a laptop. Laview code.

Problem:

NIMAX does not recognize the HP3962 when using the GPIB-USB-HS hub, on the laptop, although it recognizes seveal other instrument, like the K2000 dvm.

Thank you for suggestions, Philippe

[Filou2]

note added after my original post: I seem to remember that several "languages" can be used over the GPIB hardware. 

- the K2000 dvm (Keitley 2000) communicates with the so-called SCPI language over GPIB. This dvm can also be set to "talk" lang199.

- now, I'm not sure which "language" the HP3962A spectrum analyzer is using, but this intrument was perhaps available before the SCPI agreement took place. 

would this explain why a "lang199 only" instrument is not recognized by NIMAX ?

thanks you all for more advice, Philippe

[crossrulz]

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Filou2 wrote:

would this explain why a "lang199 only" instrument is not recognized by NIMAX ?

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What exactly do you mean by "not recognized"?  If you are using GPIB, the instrument should be detected (able to detect something is at the instrument's address).  If it doesn't know SCPI, then the IDN? will fail and the instrement won't be able to be named.  But you should still be able to talk to the instrument using MAX, assuming you know the commands to send.

[Dennis_Knutson]

Actually, the idn command along with others such as tst, rst, etc., is defined by IEEE-488.2 and not scpi but the advice is correct. If the instrument is listed and only fails the id query, then just ignore the message. The actual detection of an instrument is done with very low level GPIB commands that have nothing to do with scpi.

[Albert.Geven]

Hi

You are using old instruments but relative easy ones.

One problem could be the default settings or a very long gpib cable.

In MAX I suggest to changes the default settings for bus speef from 500ns to 2 microseconds. The instruments determine the speed anyhow and like me, old instruments are not so fast...

[Filou2]

thank you all for input (kudos follw).

"HP3562A not recognized" refers to the observation that the GPIB-USB-HS is recognized as GPIB0  by NIMAX but not this particular attached instrument. Other instruments, like the said K2000, are recognized. Cable length is 1.5 meter. I'll play with bus speed, as suggested.  I shall look into the "passport issue" as well.

I wish you all a nice day, Philippe

[Filou2 · Accepted solution]

after removing the 1.5 m long GPIB cable, and connecting the GPIB-USB-HS unit directly to the old HP3562A unit, NIMAX does recognize this instrument (low level).

Direct com over NIMAX does not process, but the (old) LabView code written for reading out the data works.

Perhaps bus speed was the issue.

Solved for now, thank you all.