package edge detection with fiber optic amplifier WLL190T

Dear all,

today we received an interesting request from a customer.

This customer wants to detect objects on a conveyor belt and needs a 50ms one shot impulse everytime when a object leaves the detection area of the sensor according to the sketch below (eg. to trigger a barcode reader or a printer at the end of the package). 
In general the edge detection is created in the PLC of the customer but in our case, this wasn't possible and the customer needs the edge signal directly from our sensor.
 

A German customer for juice packagings once told me he always uses the trailing edge to detect objects on conveyors because by doing so, he reaches the most precise and speed-independent detection of his juice packages.
 

The WLL190T (or WLL80) has a rising or trailing edge detection function:

The length of the one shot impulse has to be set in the Timer settings (on&off delay are blanked out in edge detection mode):

If you have to choose the rising or trailing edge, it depends if you have light or dark switching adjusted and if you have a proximity or through beam fiber.