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I have experience with Omrom PLCs (company only uses Omron) and mostly have used them with on/off control. If we used an encoder it fed into another unit and output to an input when the desired length was reached. Now we are using Omron CQM1 and recently got a CP1H modular PLC that can count using an encoder. We have a 500PPR encoder that works on DC24V. We want to measure a straight piece of plastic product to verify if the length is cut correctly.

I would like a basic outline of how/or where to bring in the pulses (DM??) from the encoder and measure the linear product to see if the length is correct. We are using a 2 channel quad encoder with an A and B channel. The reset will have to be by a switch after on piece is checked. The plastic part is straight and looks like a ruler. The operator will put the part in the small check and there will be a sensor to reset the counter, then it will feed forward and the encoder will check the length in millimeters with a small plus or minus tolerance. We will have a small Omron HMI to verify good or bad. I just need help getting started with where/how to we bring in the pulses, scale it to calculate length, sampling rate, etc. Basically an outline of encoders/PLC 101 for measuring a straight liner product for checking length and good or no good output. Is there anyone here who has Omron encoder programming experience for measuring? I have read the manuals and the one example and its not much help. PLEASE HELP ME!

I haven't had any experience with Omron controllers, but I programmed AB SLC-500s and PLC-5s for a while and now work for an encoder company as an Application Engineer, so I may be able to help.

The application sounds straight forward enough. zero controller, count pulses till you hit limit, factor in pulse to millimeter ratio, compare to preset and display go/no go

Typically you can wire directly into the controllers' DC inputs, as long as the power rail for the encoder and controller have a common signal ground.

How many pulses per millimeter are you scaled to? (or mm/Rev)
What is your desired tolerance?

If it is loose enough, and you are running in one direction, you may not even need to bring in the B channel.

Feel free to contact me directly with any questions.

Jim Miller
Application Engineer
Quantum Devices Inc.

jmiller at quantumdev. com
www.quantumdev.com

The frequency of the pulse train from the encoder will determine the programming approach. If the frequency is reasonable low you can use the count and compare functions and give a yes/no output or if the frequency input is high then you will have to use the high speed counter/interrupt functions. The high speed counter is available in CQM1 CPU43 models.

Hello DLB54,

Did you get any help with the Omron encoder issue? I have to do much the same as you were asking about, and also have never done it before. If you got anything useful I would be grateful for a copy.

Many thanks,

Al