Issues with communicating with two channels of a Keithley 2220-30-1 Dual Channel Power Supply

[dglock18]

We use a VI program to communicate with a Keithley 2220-30-1 Dual Channel DC Power Supply. When we try to communicate with both channels simultaniously, an error message randomly appears:

Error -1073807360 occured at an unidentified location

Possible reason(s)

VISA: (HEX 0xBFFF0000) Unknown system error (miscellaneous error)

This originates from the Keithley VISA driver. When I use another VI program to communicate with only 1 channel on the power supply, the program runs perfectly, using the exact same VISA drivers in the block diagram. I have tried many things to solve this issue, with no success. I have attached the VI code on this post to give clarification to my problem. Where would be the best place to start to fix this?

Thanks, dglock18 

[JÞB]

change the VISA reads and writes to "Synchronous"  Right-Click>>Synchronous I/O Mode>> Synchronous.  the watchband glyphs are a dead givaway that "Asynchronous" is selected.

Keithley may eventually learn to properly buffer commands.

[Dennis_Knutson]

Niether the instrument or the GPIB standard supports simultaneous communication. GPIB is and will always be a sequential communication bus. Jeff''s recomendation forces that on your program but it should be rewritten to reflect reality.

[JÞB]

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@Dennis_Knutson wrote:

Niether the instrument or the GPIB standard supports simultaneous communication. GPIB is and will always be a sequential communication bus. Jeff''s recomendation forces that on your program but it should be rewritten to reflect reality.

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Keithley's are notorious for having commands with different priorities.   Getting two nearly simultaneous "Immediate" commands is something their FW designers could have handled "more elegantly."

[dglock18]

@Dennis_Knutson - I understand, and thank you. I figured that was the case, but are you saying I should rethink my logic entirely for communicating with the Keithley? How would I be able to communicate with different two channels another way? I am fairly new to the Labview community... I'm sure this is a relatively easy fix

[dglock18]

Thanks Jeff! I'll try it and report back to see if that resolves the issue entirely. 

[Dennis_Knutson]

You could use the error in/error out wires to enforce dataflow. Don't have communication structures that execute in parallel. Use a single Action Engine for all communication. Use VISA Locks. All different possibilities.