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Strange behavior

The issue is that everything works, but the instrument itself is always a step behind the front panel.  I.e., I flip the Hi Res switch and nothing happens, then I flip another switch, say the damping switch, and then the Hi Res responds.  I then flip another switch, and then the damping resonds.  The switch controls the correct parameter, but it is always behind by one action.

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Message 1 of 7

Hi Jack,


so there is a problem with your VI, but there is no VI with your message...

Which kind of answer do you expect with this little information?


Generic answer: this sounds like a race condition problem...

Best regards,
CLAD expired, using 2009SP1 + LV2011SP1 + LV2017 (+LV2018 sometimes) on Win7+cRIO
Kudos are welcome Smiley Wink

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Message 2 of 7

My guess is you are missing a termination character or something in your message so the instrument is stuck looking for the end of the message.


What instrument are you using?  Can you share you code?

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Message 3 of 7

The problem is with the wiring in your block diagram.  Fix that and it will be fine.Smiley LOL

"If you weren't supposed to push it, it wouldn't be a button."
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Message 4 of 7

Sounds like you have a bug in your program.


Without seeing your code that's all the help we can give you.

Unfortunately, most readers of this Forum, including some real Experts, have not mastered the skill of being able to read the code that Posters fail to post. If we cannot see "what you did wrong", we are unable to tell you how to fix it. (Bob Schor 28 August 2018)
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Message 5 of 7

See here for excellent advice on diagnosing strange behavior


Always maintain an accurate count of deployed mousetraps.
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Message 6 of 7

Yes, we cannot debug sentences to fix your race condition.


Without knowing anything about your code architecture, we are all stabbing in the dark.


One thing that has not been mentioned is a scenario where your control terminals are before (or in parallel) to an event structure that gets triggered by e.g. a value change of same. The terminal gets read at the beginning of the new iteration and way before a value change triggers the event structure. Now the new values is only read from the control at the next iteration.


Please attach a simplified version of you VI and we will be able to help you.

LabVIEW Champion Do more with less code and in less time
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Message 7 of 7