VISA Read Double Precision Number Corruption with the Keithly 2400

[BSteele]

I am stumped on this item.  I have two PXI systems with built in GPIB controllers.  One of the systems randomally started showing behavior where the double precision read commands returned gibberish data.  On the other system, I am using the exact same code and everything works.  Standard String commands work just fine (set voltage, set current, query set voltage etc.).  I have tried the following:

Reset computer

Swapped Keithly instruments (the problem follows the PC)

Swapped GPIB cables

Updated 488.2 driver

Used seperate HS-USB to GPIB controller.

I will be reinstalling NI-VISA as well.

The only difference is that I installed some other LeCroy instrument drivers to the failing system.  But the problem didn't occcur after I installed the drivers, it occured while my code was running.

Has anybody ever seen this before?  What could other causes be?

[Albert.Geven]

seems like the problem could be that the power of the gpib is not good or the speed a bit too high.

Did you try to set the speed of the gpib to 1microsecond?

Just a lucky guess maybe but the 2400 is ot very fast and if power supply is scarce it could be the problem.

[BSteele]

Thanks, I will look into it.  The real problem is that I have another identical system (initially) where everything is running just fine.  And it has worked for 2 years previously.

[BSteele · Accepted solution]

The problem was with the Keithley, it was changing the format of the data without my knowlege.