I have a single digital input that will cycle on a regular basis.  I simply want to look at it over a short time frame (10-90 seconds) and determine how often it is cycling per minute.

I am working with Logo!Soft Comfort version 8 and a LOGO 8 processor and currently using FBD mode.

I am using an Asynchronous Pulse Generator to provide a repeating known time for counting the machine cycles.  I am using a Up/Down Counter to count the actual machine cycles and then resetting it each time using the output from the Asynchronous Pulse Generator. The CNT output of the counter is linked to a Mathematic function to multiply or divide it (based on how long I am monitoring) to get machine cycles per minute.  I use the output of the previously mentioned (or separate, tried both) Asynchronous Pulse Generator to trigger the Mathematical function to activate and do the math.  It is set to keep the last value even when its trigger goes back to 0.

This works fine except for timing.  Since I have to reset the Up/Down Counter and time that with activating the Mathematical function it gets ugly.  I cannot seem to figure out a one-shot method to trigger the math function at the right time and if it is triggered for too long it gets the new reset number from the Up/Down Counter to apply the math to. If I reset the Up/Down Counter too quick the Mathematical function still gets the new reset number.

Maybe the problem was the FBD style in general.  Using normal LAD I could control the order of operations a bit more maybe so I tried going over to LAD style.  However, the Asynchronous Pulse Generator I want to keep this timer repeating doesn't have an output to use!!!  I must be missing an easy way to do this  Any help???

Thanks a million.

AWESOME!  Due to the name of the function I never looked at it.  I assumed it was having to do with testing whether an analog input was above a certain threshold or not.

Thanks for the reply!!