read loops

that is what I am suspecting.

From this input, I want to see the maximum amplitude that the positive pulse reaches. (or at least if it is above an amplitude I set)

Where is this analog input coming from. Why is an analog input pulsing?

I agree with Bit Bucket 07 this is not a scan time issue, it's a analog input card's update issue.

Important question: what is the frequency of this pulsed input?

The PLC scan time is usually under 10ms for that model, but the analog input update time might be around 100ms (wag from memory).

EDIT: On the expansion module advanced configuration you can adjust filter settings which affect update times. The fastest for a 1762-IF4 will be 130ms and can be as slow as 530ms. The default is 450ms.

What is the duration of the pulse?

Also, can you share your logic? (zip it and attach to a post)

that would explain then - the total period is only about 200ms. So my positive pulse is about 100ms. I'm surprised it works as often as it does!

thank-you everyone for your help on this matter! I will have to find a workaround.