How to program this

[userxyz]

I have 2 carpetdetectors on a machine, at the input and the exit of the machine. When there is acrpet in de tha machine a motor has to run.

You could say, start/stop, but no. Sometimes there are small pieces of carpet to be producted. So when a reset came it could be possible that there just was a set of another carpet...

 

[Steve Bailey]

A simple method would be to keep it running for a minimum period of time after the trailing edge of the carpet has cleared the sensor at the entrance. A potential application for an off-delay timer if your PLC has one in its function set.

 

[SimonGoldsworthy]

Use the input sensor to count up and the output sensor to count down. When the count is zero turn off the motor.

 

[jstolaruk]

I would use both Steve's and Simon's approach. When the counter indicates zero products inside let it run long enough to empty out any that were missed going in.

 

[userxyz]

Hey

Hey

I've thought also to use a counter, but..., is this safe enough ?

 

[TConnolly]

Increment the counter on the leading edge of the input sensor pulse. Decrement the counter on the falling edge of the output sensor - this way you know the roll has completely exited the machine.