Error 1 occurred at an unidentified location

Question

Good morning,
I've gotten the error shown in the screen capture below on a few occasions now.  It started occurring when I began running two different experiments from the same CompactRIO hardware.  I have a single target which scales all of the data, does alarm checks and writes the data to network shared variables.  Two separate host vi's generate graphs and log data to separate text files.  Previously I had one target vi and one host vi running just one experiment.  Besides the fact that this error is completely nondescript, I don't see how adding a second host vi (plus some additional code to the target vi) could cause this issue.  This will occur at random times when no changes have been made, so I'm not sure how an input parameter can suddenly become invalid if nothing has changed.  I'm unsure if the target vi pauses when this error occurs, but I know from my datalog files that when this error occurs both host vi's do nothing until I click continue.  So far every time this has happened I've clicked continue just once and everything ran normally again for several hours (or days) until I got the error again.  Any thoughts/suggestions would be appreciated.
Dave
Attachments:
Labview error.png ‏32 KB

Answer 1

Hello Dave,
Unfortunately, due to the nondescript nature of the error, it is extremely difficult to comment on what could be causing it.  My first thought is that both hosts are pulling information from the same location, and a race condition exists that only manifests itself occasionally.  That is, if the hosts are alternately grabbing data, you will be alright as long as data is available.  However, if they attempt to grab data and it doesn't exist because the other host already grabbed it, an error could be thrown.  Are your hosts both running the same VI?  Do they access data from the same locations?  Do you use any local variables, which can lead to race conditions?
It would definitely be helpful to try and pin down where the error is occurring.  To do so might present some difficulties.  You could create a subVI that logs error messages along with information on what function just executed, and place this subVI at various key locations in your code.  Then, when the error is thrown, you could go into the error logs to narrow down where the error was coming from, and debug that portion of the code to ensure no invalid or empty characters are in use.  Remember that an empty string could cause an invalid character; for example, if both hosts were looking in the same location, one would find data and remove it while the other finds nothing.
If the error itself is not causing any negative behavior, then you could introduce error handling code that would check error conditions and remove the Error 1 before it was thrown.  This would allow your code to continue running after the error was thrown.  However, since you are not aware of the source of the error, it may not be the best idea to simply ignore the error indefinitely, as it could eventually manifest itself into a worse error.
I'm afraid I can't offer much more insight without more information on your code, what it is doing, how it is written, and how the hosts are interacting with the target.  Hopefully you have made some progress in narrowing down the cause and debugging your code.
Patrick
CLA