GE Fanuc math blocks

[Dave Powers]

I have a register that I would like to increment by 1 whenever an alarm comes on so that I can keep a running total. My problem is that the math block seems to keep adding 1 to the register every scan. The math block receives power from a contact that closes when an alarm occurs, this sets a bit in the alarm register, and it also adds one to the alarm count register. Whenever the alarm contact is on, the alarm count register keeps counting. It doesn't just add one to the register. Is this normal for an addition block to keep counting every scan?

 

[PLucas]

Yes, this is normal, use a one shot to trigger the addition block.

Paul

 

[PLucas]

I had better qualify my answer above.

The only GE PLC's I know is the Series Six, that is what I based my answer on as I could see know reason why other GE PLC's are any different. Then again I have never really noticed if any other PLC's (different brands as well) behave any differently than this as I have always triggered addition blocks using a one shot.

Paul

 

[Dave Powers]

Thanks, I thought that would have to be the way to fix it.