Problem: Labview 5.1 & HP 34970A via GPIB

[koutatelazzo]

Hi all !

I'm a total novice in Labview, but I have to control a HP 34970A with a
20-port MUX to read VDC signal from two dp-cell, a mass flow meter and a
thermocouple. I own a GPIB card (PCII) and I use Labview 5.1 on win95.

The problem is this:
the VISA initialization VI finds the HP, and correctly identifies it (with
the correct GPIB port). But, when I try to read or write (with the VISA
read-write VI) or when I use the HP drivers (found on the National
Instrument site), I obtain an error, which explanation sounds like "VISA
hasn't sufficient information on instrument location". This thing happens
even also when I send a simple request (as the IDN request), via the VISA
read-write VI.

Is it a driver probl
em, a HP problem or a GPIB problem ? I think it is a
driver problem (the GPIB software identifies the Hp). How can I fix it ? I
have downloaded the Labview driver of the HP, but I've noticed there are
also the LabWindows drivers....

Thanks for any advice ! I hope I have explained well the problem...

Regards,

Tetrazzo


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[Brian_Vibert]

The labview drivers on NIs web site and the ones that ship with the 34970A are not very good. However they should be good enough to get you started. First make sure you can communicate through MAX or VISA Interactive Control by sending it a few simple commands. Then you should be able to use the initialization vi for the 34970A to start your VISA session, next you could try VISA read/write or try some of the sample vis. Make sure you close the session at the end.

Attached is a vi that I just verified on a win95 with LV 5.0.1 and a 34970A using GPIB.

I hope this helps, feel free to ask any other questions.

Brian

[per.watson]

Instead of using VISA try using just the 488 or 488.2 vi's to communicate
with the HP. Verify you can read/write using the GPIB vi's. The logging
system I built uses just the 488.2 vi's and works fine. I found the 34970A
sample vi drivers didn't always works correctly.
"koutatelazzo" wrote in message
news:384788001.985023910852.JavaMail.root@web572-mc...
> Hi all !
>
> I'm a total novice in Labview, but I have to control a HP 34970A with a
> 20-port MUX to read VDC signal from two dp-cell, a mass flow meter and a
> thermocouple. I own a GPIB card (PCII) and I use Labview 5.1 on win95.
>
> The problem is this:
> the VISA initialization VI finds the HP, and correctly identifies it (with
> the correct GPIB port). But, when I try to read or write (with
the VISA
> read-write VI) or when I use the HP drivers (found on the National
> Instrument site), I obtain an error, which explanation sounds like "VISA
> hasn't sufficient information on instrument location". This thing happens
> even also when I send a simple request (as the IDN request), via the VISA
> read-write VI.
>
> Is it a driver problem, a HP problem or a GPIB problem ? I think it is a
> driver problem (the GPIB software identifies the Hp). How can I fix it ? I
> have downloaded the Labview driver of the HP, but I've noticed there are
> also the LabWindows drivers....
>
> Thanks for any advice ! I hope I have explained well the problem...
>
> Regards,
>
> Tetrazzo
>
>
> ______________________________________________
> FREE Personalized Email at Mail.com
> Sign up at http://www.mail.com/?sr=signup
>
> --
> Posted from 131.175.67.92 by way of rmx308-mta.mail.com [165.251.48.43]
> via Mailgate.ORG Server - http://www.Mailgate.ORG

[koutatelazzo]

"per.watson" says:

>Instead of using VISA try using just the 488 or 488.2 vi's to communicate
>with the HP. Verify you can read/write using the GPIB vi's.

The GPIB "idn" command works, so I think the GPIB communications are
correctly configured.

> The logging
>system I built uses just the 488.2 vi's and works fine. I found the 34970A
>sample vi drivers didn't always works correctly.

Thank you very much for your help. Now I'll try....

Thanks again and excuse me for the nickname change....

Regards,

Tetrazzo


----------------------
Tetrazzo
Honda CB250N '79

koutatelazzo@usa.com

[koutatelazzo]

"per.watson" says:

>Instead of using VISA try using just the 488 or 488.2 vi's to communicate
>with the HP. Verify you can read/write using the GPIB vi's. The logging
>system I built uses just the 488.2 vi's and works fine. I found the 34970A
>sample vi drivers didn't always works correctly.

I can't figure out how to configure the 488.2 vi's: I'm a *total*
novice of labview, and the vi's are too complex (have a lot of input
and output....). I thank you very much if you can send me a simple
example (read temperature, or read vdc signal, or similar), so I can
view your implementation and develop my own implementation.

I thank you very much for your help, and excuse me for the trouble.

Regards,

Tetrazzo
koutatelazzo@usa.com
---------
-------------
Tetrazzo
Honda CB250N '79

koutatelazzo@usa.com

[Battman (battery man)]

I'm porting some VIs over to the 34970A, and had similar problems running the Demo VIs from HP.
The answer to my problems was a timeout value set to 320,000 in several of the VISA opens. Apparently the number is too big, and I don't know why HP would have set it so high (5.5 minutes) - I think it was a typo.
What is interesting, in my case, was that I could commumicate with the instrument (Open, Setup and Read back data) but the problem occurred when I tried to call VISA Close.