Measuring cloth length using an encoder Mitsubishi FX PLC

Hi guys,

I want to measure the length of a piece of cloth that is produced by a machine using an encoder and a mitsubish FX PLC. I don't really know where to begin, could anybody help me and possibly give me and example program?

I know how to read the encoder value and set it up as we currently use this in some other systems but don't know how to use it for measuring.

Just a note... there is backlash in the gearing due to the way the cloth is produced, this can not be changed.

Thanks in advance
Mark

Wel I assume you an read the pulses from the encoder so i suggest you use a sensor to detect the leading edge of the fabric, use this to reset the encoder value on a pulse [PLS]then use the same signal on falling edge PLF load the count into a 32 bit register then divide it by number of pulses per mm/inch/foot/yard etc.
this will give you the length in what ever you desire
so for example if the count is 50 per mm just divide the pulses by this figure

And if you are getting backlash try using the A & B signal from the encoder for adding and subtracting from the counter.