GPIB Bus time

[ABru]

Hello,

I have a very old controller connected to a new computer via GPIB.

I know it needs the bus time to be 150usec.

The longest option I see in the Measurement & Automation Explorer is 2usec.

How can I change it to 150usec?

Thanks!

[Albert.Geven]

A bus timing of 2 uS means that signals do not change during that time.

Did you try simply 2 uS already?

150uS is not slow but prehistoric

[ABru]

I tried the 2uS, it didn't work.

The equipment is prehistoric too, so it's OK.

We had this problem already when we switched from the 'very old' computer to the 'just old'.

Somehow, it was solved.

Now we switched again, to a new computer, and it needs to be solved again.

I'd really appreciate any help with this.

The card is PCI-GPIB.

Thanks.

[Kracken]

Hi ABru,

Do you still have access to the "very old" or "just old" computer?  If so, check to see what 488 driver is installed. 

What operating system are you running on the new computer and the old computers?  It is possible that 150 us was an option in one of the older 488 standards, but any driver that old will probably not run on a modern operating system.  The oldest GPIB driver I could locate is from 2000, and it still only has 2 us as the slowest option.  That is the NI-488.2 v1.0 driver, and it is designed for Windows 95 or Windows NT.

Unless there is some method that I don't know about to change the bus time to a non-standard time, I think your best solution is going to be to upgrade to a new instrument.

Regards,

Brandon V.

Applications Engineering

National Instruments

www.ni.com/support

[ABru]

Hi Kracken,

I do not have an access to the old computer, it's dead.. 😞

Both old and new computers run with WinXP.

I was told there's a method, only noone remembers how it's done..

[Curt_C]

Hi,

You might be able to do this using the ibconfig function.

Check NI-488.2 function reference manual

ibconfig (int ud, int option, int value)

One of the option parameters listed in Table 1-5 in the manual is

IbcTiming

values listed:

1 - 2us

2 - 500ns

3 - 350 ns

Maybe if you play around with others option values you might be able to get that to work.

Curt

[Albert.Geven]

try a very short cable and see if this helps.

Also if you are using a USB GPIB system use a powered hub

[Kracken]

Hi ABru,

What are you seeing when you try the 2 μs option or either of the other two options?  Do you get an error code?

What instrument are you using?  Are you able to send it simple identification commands?  Are you able to scan for and find your instrument in the Measurement & Automation Explorer?

How long is the cable you are using?  Have you tried other cables?

Have you tried using the PCI-GPIB with another instrument to verify that the card works?

Regards,

Brandon V.

Applications Engineering

National Instruments

www.ni.com/support

[ABru]

Hi Kracken,

I get an error code 6 (I/O operation aborted).

The device we try to connect is a controller of a superconducting magnet, made in the 90's, by Cryomagnetics.

I'm not able t send simple comands, but I do see it in the scan @ Measurments & Automation explorer.

The cable is about 1 meter long. We tried other cables too.

Other instruments do work with this card.

Here are the computer specifications:

New computer 
WinXP
One board PCI-GPIB/TNT5004 (S/N-109E87C) which they move from PC to PC.

LabView 2010
The drivers on the new computer are:

NI-488.2 2.7.3

NI-VISA 5.0.0

Old Computer 
WinXP
LabView 2009
Drivers on the old computer:

NI-488.21.70
NI-VISA 2.6.0f7

We also tried to put the hard drive to a different old computer, and it didn't work either.

Thanks,

Anna

[JasonSmith]

ABru-

The most obvious difference--aside from the new computer--is that you were previously using NI-488.2 1.7, and you are now using NI-488.2 2.7. Version 1.7 is extremely old, and we do not like to recommend that people use it, because it is no longer maintained, and does not support much of our current hardware and operating systems. It can be used with Windows XP, but will not work with Windows Vista or Windows 7.

Version 1.7 is a completely different driver architecture than the current 2.x drivers, so it does have some behavior (primarily timing) differences. I would recommend that you try using the 1.7 driver, to determine if that is the cause of your issues. While this may work short-term, it is not a long-term solution since it will not work with newer operating systems or hardware.

If version 1.7 works, the best long-term option would be to use a GPIB analyzer, such as a PCI-GPIB+, to capture the low-level bus activity of the system working with 1.7, and failing with a newer driver. If we can use this to identify the cause of the failure, it may be possible to fix in a future driver version.

-Jason S.