Undesired GPIB activity when end module

[Bob Balch]

When TestStand unloads a CVI step or when pressing terminate for a CVI project, Some activity occurs on the GPIB bus that causes a power supply to go to zero volts. The address of this instrument is 3. What's happening and how do we prevent it? We'd like voltage levels to remain constant from step to step.

[Aaron B.]

Hello Bob,

We could use a little more clarification if you do not mind. Is this behavior observed when unloading any CVI step or just a particular one? Does that step have any GPIB code within it or in the same project as it? What do you mean by "pressing terminate for a CVI project"? Does this mean that you terminate the execution of the TestStand engine while it is running a client sequence file that contains CVI steps? When you say you unload a CVI step, are you using the option to unload after each step? If you do not use this option and unload everything statically after an execution, do you get the same behavior?

Without knowing anything else about your system, I would suggest first looking at your cleanup routines in the cleanup step groups of your T
estStand sequences. Also, are there cleanup routines for your code modules that might be getting called? Please provide us with a more complete description of the problem. We will do our best to determine what can be done to fix it.

Aaron B.
National Instruments

[Bob Balch]

The behavior occurs whenever unloading any CVI Step. There are no cleanup functions defined for the steps.
Each CVI DLL is dynamicaly loaded and unloaded at step completion. This option was chosen to correct other problems.

The behavior also exists when operating without TestStand, using only the CVI environment. If, when debugging, the Terminate button is pressed once to break and a second time to terminate, something goes out on the GPIB bus resulting in a GPIB controlled power supply to be set to 0.1 volts.

[craigherdman]

Bob,

What version of the NI-488.2 driver do you have? Tell us a bit more about your system (OS, version of CVI, type of GPIB card, etc.) So it seems that when you halt your application that something happens on the GPIB that sets the power supply to 0.1 volts? You can run NI-SPY to see if there is any driver call that would be causing this and if you have a PCI-GPIB+ board then we could actually analyze the lines on the bus. NI-SPY might be our best bet.

Craig H.
NI Applications Engineering