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Checking the length of a product


How do I check the length of a product with your controller?

The only way known to me is a work-around using a photocell signal and connecting it to 2 inputs, one to a product detect and the other to a sync-point or reorder-point.



The photocell signal will look like


We want to measure the distance between the beginning and the end of the product with a sync-point.

Obviously, if the falling edge is not within limits, the product will be declared as bad (red product) and rejected.


Connect the photocell to 2 inputs (the 2nd, you have to parallel signal and ground). Here input 1 and input 2 as an example but it can be any input.

Declare3 for example a product detect 1, use the raising edge of the signal to detect the beginning of the product.




Since the product length is 88. We want to check that the length is between 87 and 89 with a sync point.



Since it is the same signal but just using 2 inputs, it will measure the distance.