PID Controller Design for Servo Motor by Using PLC

zee · Apr 28, 2014

Hello, I'm student from Malaysian and currently doing a final year project about PID controller design for servo motor by using PLC. If you dont mind, I'm just wanna asking and need your advice about why my PID block always error and it describe that it 'not mapped' in my program??? I'm very sure that the destination of my PID block (input data word, 1st parameter word & output data word) are set rightly based on my PLC. For your info, I'm using PLC OMRON SYSMAC CPM2A and CX-Programmer...Here I attach my programme..tq

osmanmom · Apr 29, 2014

1.) select PID

2.) select SET (select ASFT)

3.) OK

Peter Nachtwey · Apr 29, 2014

zee, are you trying to control position or velocity? Controlling velocity is not hard but controlling position will be challenging.

zee · Apr 29, 2014

Now I'm trying to control speed of servo motor. My program always have an error. If you don't mind, can you check my full program because I'm not sure with my own program. Before I connect it with my hardware, I really hope that my program didn't have a problem..=)

osmanmom · Apr 29, 2014

to help you,

you need to help us by provide the best info by picture,sketch,drawing,servo drive,cpu model,

we can give you few idea,hints other else you need do your own self.

zee · May 6, 2014

Okay, actually now my program totally can be use by using my PLC. I just want to ask one question about my hardware, is it can CE120 controller connected with PLC OMRON CPM2A??? Because I need to convert from analogue (CE110 servo motor) to digital (PLC) and vice versa. This attachment is the picture of PLC and CE20 controller that i use. TQ

osmanmom · May 6, 2014

I no experience using the CE120, I need to read the manual user for handling.

if i not mistaken your first problem is CE120 already has its own PID, but no feedback entry.

if you program on CPM2A PID, then you have 2 PID.

if you want running servo motor you should have CE110, attachment.

You need expansion Analog Module CP1A-MAD01/MAD11 if you want PID-feedback applications.

CPM2A are old model.

except another model with Analog IO.

and you need 1 type of process to implement the PID .

Lot of examples of using PID - search on the internet.

I think you need to check/revise back of your hardware/project title.

now you using educational training kit.

you need 1 simple process.

osmanmom · May 6, 2014

Old Model

CPM2A-CPU41 with Analog IO

Peter Nachtwey · May 6, 2014

I need to see a trace or trend to see what is wrong.
I don't know where the formulas for Ki and Kp came from.
It is easy enough to roll your one PI controller for speed control.
It looks like there is no encoder. Everything is analog.

What is the simulator supposed to be simulating. Only under damped second order or higher systems have a gain, natural frequency and damping factor. Usually the plant is modeled as just one gain and time constant or corner frequency.

osmanmom · May 6, 2014

Mr PN,

may you explain little bit what your mention on,

sometimes i miss-translate (mostly)

zee · May 6, 2014

Yes Mr PN. Can you explain more detail what are you mention above?
This give you my block diagram of speed loop.

Peter Nachtwey · May 6, 2014

Zee, what you have shown is a cascaded loop control with a PI controlling the inner loop and a PID controlling the outer loop. Current loops must be relatively fast. Are you trying to control this cascaded loop with a PLC?

The encoder pulses should not be converted to analog. The velocity should be determined directly from the encoder count rate.

Do you need to use this equipment? Can you use something else?

zee · May 6, 2014

Mr. PN, if I'm not converted the encoder pulses to analog, actually my servo motor trainer CE120 cannot move when I give the input at PLC (because the motor is in analog state). So, input from PLC cannot give a real command to my servo motor because of 'interruption' here. And I only have this equipment to do the experiment.

osmanmom · May 6, 2014

Time is running,

After experiment what your next step/planning?

zee · May 6, 2014

If my motor can move, I can proceed with GUI.

PID Controller Design for Servo Motor by Using PLC

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