GPIB, can't find instrument

[Fan Zhang]

Hello group,

I have a question about my GPIB interface that failed to recognize a device.
I'd love to describe the problem here and am very willing to hear your
suggestions.

I work in a lab. I used LabVIEW to write a program to communicate with a
multimeter. The program has been working very well in the past two years.
Now I want to add some function to my program so that I can control a
temperature controller at the same time as I control the multimeter. So I
connected the temperature controller to the GPIB cable of the multimeter and
asked the GPIB getting started program to scan for the new instruments.
Surprisingly, an error message saying " Scans for instruments failed because
it didn't find any instrument.". That is to say, both the mu
ltimeter and the
temperature controller can't be seen. I checked all the connections and they
are all firm. I then tried to restart the computer, reinstall the GPIB
interface, change another GPIB cable. But the problem persists.

I am now guessing that the GPIB interface of the temperature controller does
not work--it has not been used since day one so we are not sure if it came
this way or just gets "rusted" in the years in our lab. Before returning the
temperature controller to factory for a check, I wonder if any expert here
could give me some suggestions on what to try. Thanks!

Regards,
Fan Zhang

[mikeporter]

Dollars to donuts, the GPIB address of both instruments are set to the same default value--at least that's what I'd check first. Depending on the age of the instruments the address might be settible through front panel controls or perhaps dip switches. Mike...

[ian_fung]

hi,

I am not sure sure about temp. controller but does it come with RS232 interface as well? Like some of the multimeters (i.e. Agilent 34401A), they come with the option for either RS232 or GPIB interface.

If it does, you might wanna check if it is set to as GPIB interface.

Good luck to u.

[LucaP.]

Hi

How old is your temperature controller? Perhaps it's non-IEEE 488.2 compliant. Check this KB for more details: http://digital.ni.com/public.nsf/websearch/72FAD7156202DDF9862568900048F006?OpenDocument

Regards,
Luca

[Fan Zhang]

Thanks Mike. I did check the addresses. One is set to be 12 the other 16, so
I do not expect conflict. Sorry that I did not mention this in my original
post.

"mikeporter" wrote in message
news:5065000000050000001C140100-1042324653000@exchange.ni.com...
> Dollars to donuts, the GPIB address of both instruments are set to the
> same default value--at least that's what I'd check first. Depending
> on the age of the instruments the address might be settible through
> front panel controls or perhaps dip switches. Mike...

[Fan Zhang]

Ian thanks for your suggestion. It does come with a RS232 interface. So if
the GPIB port really does not work, I would be able to talk to the
instrument via it.

The temperature controller is a bit old. It is a LakeShore product that was
bought probably 10 years ago. You are right. The interface can be changed in
front panel. And it was set to be GPIB when I was trying to detect it. So it
is unlikely it is the reason. Thank you though!

Fan

"ian.f" wrote in message
news:50650000000500000021140100-1042324653000@exchange.ni.com...
> hi,
>
> I am not sure sure about temp. controller but does it come with RS232
> interface as well? Like some of the multimeters (i.e. Agilent 34401A),
> they come with the option for either RS232 or GPIB interface.

>
> If it does, you might wanna check if it is set to as GPIB interface.
>
> Good luck to u.

[Fan Zhang]

Luca,

Thanks a lot. The interface is IEEE488. So might it be the problem?

The confusing part of my problem is, why after the temperature controller is
connected to the bus, both instruments can't be seen. I really do not
understand how it could happen. Can anybody shed me some light on this?
Thanks!

Fan

"Luca P." wrote in message
news:50650000000500000038140100-1042324653000@exchange.ni.com...
> Hi
>
> How old is your temperature controller? Perhaps it's non-IEEE 488.2
> compliant. Check this KB for more details:
>
http://digital.ni.com/public.nsf/websearch/72FAD7156202DDF9862568900048F006?OpenDocument
>
> Regards,
> Luca

[mikeporter]

Ok, step 2.

If you hook up just the new instrument can you see it?

Step 3:
Forgetting for a moment the automated function for finding the instruments, can you send commands to the two instruments even though they aren't "found" by the utility?

Mike...

[DiegoF]

Hi Fan,

I'm curious to know the answers to the questions that Mike asked, specifically:

>>If you hook up just the new instrument can you see it?

>>Forgetting for a moment the automated function for finding the instruments, can you send commands to the two instruments even though they aren't "found" by the utility?

I think does questions are important.

DiegoF
National Instruments.

[microes]

Hi,

how is it possible to type over commands to the instruments first even when it can't be detect in 'Scan for Instruments'?

I'm facing the same problem too but i'm a begineer in this starting to grasp the understanding of Labview program.

Thank you