Another shift register problem

First of all I want to say that I learned a lot from this forum and thank you all for that.

I am trying to retrofit PLC in one of our cartoning machine.

Some data:

Old Plc: Eberle

Central drive: AC motor with inverter coupled to the central shaft by electromagnetic clutch.

Mechanical cam switch (gluing, vacuum operation, ejecting etc)

Original program-No original listing



New PLC-Omron CJ1M CPU 22



We plan to replace the mechanical cam with incremental encoder and software cam (BCMP2)-PLC scan time around 2 ms so this should work without interrupts.

Max speed of the machine: 100 cartons per minute.

Machine pitch: 6 inches

Tracking of the cartons/pooches by two parallel shift registers.

The problem I have is that sometimes during production mechanic has to readjust the machine an during that he uses the hand wheel to drive the machine -moves back and forward over the shift point, so after that positions in shift register are/could be wrong.

How to fix this problem?



Thank You in advance.

Hello

Welcome to the forum.

I would use an absolute encoder if the shaft doing on cycle fer unit.
Omron support gray code so you can be sure if the operator move the shaft manually the PLC will follow it.
If are going to use incremental encoder use High Speed Counter.
Regarding the shift register check SFTR(084) - Reversible Shift Register.
So you will need to know what direction shaft rotate (by the encoder) and move the data forward and backward.

1 turn of the shaft=1 cycle (unit)
Hand wheel operation also turns the encoder shaft.
Yes I plan to use HSC but comparison is done in normal operation withot interrupts.
Reversable shift register is an option but since I am begginer I can not figure out how to write ledder program to shift left end right regarding to the movement of the machine.

If I was in your place I would considering of using absolute encoder.
Absolute encoder give you the position of the shaft at any time.
even you shut off and turn on the power.
With HSC you will need do homing.
Regarding the shift register,how long it should be?
You can create some registers and move data forward and backward.
But it hard for more then few steps.
The SFTR would solve that problem.You will have to spend some time to learn that.
All the people here started from the begetting.
Every day we have to learn something new.Experience make it easy.

When I started I hadn't the privilege to be member of this kind of forum.I had to deal all by my self.
You should consider your self as lucky one.