Getting Logix math overflow minor faults

[patjdixon]

I have Logix v21 running in Emulate. I am getting runtime faults at random times, typically it takes anywhere from 30 seconds to 5 minutes for the faults to occur after being placed in RUN. The major fault is a watchdog timeout, but before that I get a bunch of math overflow faults on Sheets 1 at location D2. I removed blocks in D2 and still get the same faults (see attached).

Any ideas?

 

[gclshortt]

http://www.plctalk.net/qanda/showthread.php?t=34018

http://www.plctalk.net/qanda/showthread.php?t=111024

The above threads may help you out.
Regards,

 

[patjdixon]

Thanks gclshortt. I am looking through the links, but since I have nothing in D2 of the sheet I don't understand how I can have a math overflow.

 

[Gadelric]

The last time the math function ran, it did the job requested and, from what it sounds like, your fault came up. Removing the function from the logic doesn't reset the values that the math function performed. Monitor your tags, clear out the data the math function did and see if you can run without the error returning.

 

[patjdixon]

How do I clear out the data the math function did? Won't this happen when I clear the faults and put the routine back in RUN mode? I assume whatever happened when the fault occured is cleared when the faults are cleared, the routine goes offline, and then I set it back to RUN.

I still don't understand how it is pointing to D2 when there is nothing there.

 

[patjdixon]

With no substantive code changes, it has been running without fault for the last hour. What the heck?

 

[patjdixon]

Ran all night long with no code changes and no faults. I have no idea why the faults happened.

 

[Gadelric]

Welcome to the world of programming my friend.
Being that you never figured out exactly what happened, or what corrected the issue, in time this gremlin may pop back up.
In my experiences, there are some things that I have come across that I still can't provide an answer to what exactly happened. These things usually come up when I am trying to utilize a feature that I have never used before, generally speaking it falls into the category of what I call Code 90 (operator error).
With your program running stable now, I wish well.

Be safe,

Gad