GPIB locks up after about 15 minutes with a VISA Write Timeout Error

[Roese]

I am using GPIB to control two electronic loads.  After about 15 minutes of runtime on the program, the GPIB communication locks up.  A probe reveals an error message about a Visa Write Timeout.  When this occurs, I have to stop the program, cycle the power on the two loads, and then restart the LabView program. When addressing the loads, I use the same routine every time.  1) Initialize communication, 2) Send command/request, 3) Close communication.  I thought I might have been overloading the GPIB bus, so that's when I added the close command after each sequence. However, it didn't seem to make a difference.  Could there be a compatability issue with the GPIB of the loads and the NI GPIB or Windows version? (I'm using XP and LV 10)  The electronic loads are older models, so I'm not sure how that impacts this scenario.

[Citabria]

You're controlling two separate loads with two unique GPIB addresses, correct? If so, signal collision could be a possibility. Are any of your GPIB call querys? If so are you waiting for the return message before calling the next query? Collisions are common with GPIB and the symptoms can be exactly as you described. Something will "work for a while" and then errors and lockups will occur.

[Dennis_Knutson]

There should be no need to run an initialize and VISA Close function more than once. What are the loads and are you using an instrument driver from NI? Is the driver or your code doing an instrument error query to see if the instrument is reporting a problem?

[Roese]

The loads have unique addresses.  There shouldn't be any signal collisions.  I am using them in the same state machine, so one call finishes before the next call is begun.

[Roese]

They are Chroma loads, and I am using software off of the vender's website.

[Dennis_Knutson]

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@Roese wrote:

They are Chroma loads, and I am using software off of the vender's website.

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That's kind of vague. What model and what web site? What about my question on the error query?

[kcarbon80]

What was the solution to this problem?  I am using a Chroma load as well (model 63802) and I seem to have GPIB lockup issues.  How can I clear the GPIB lockup without manually turning on and off the load?  I am trying to control the instruments from my remote desktop connection.  Thanks.

[Thomas-B]

Hi kcarbon80, 

As this thread is over 2 years old, I do not know what solution was found for the previous problem being addressed, if any. However, if the device is locking up in the middle of your program, you may want to try clearing the device programmatically using the DevClear.vi that comes with the NI 488.2 driver. 

I hope this helps.