RSLogix 500 Emulate PID Problem

Greetings,

I am currently trying to program a basic temperature loop for a Allen Bradley Micrologix 1000 plc.

I have installed :

RSLogix Micro Starter Light
RSLinx Classic light
RSLogix Emulate500

All programs are running and I have programmed a simple start stop rung to prove they system is working, which it is.

I have also trialled an SCP block, which is also working.

My problem comes when trying to use a PID Block.

My block is set-up as follows:

PID FILE = PD10
Process Variable = I:1.0
Control Variable = N11:0

I cannot get the PID block to change state to "Enable" so "EN" flag =1

I have a feeling it is something to do with the emulator software and the debugging report that the emulate software uses.

Does anyone have any ideas on how I might get the emulator to work with the PID block??

I have attached a screenshot showing the program, rung, I/O, EMU & Linx

Any help greatly appreciated.

Thanks


Bwengis

A ML1000 does not support the PID instruction. ??? What processor do you have configured?

RSLogix Emulate 500 does not support the PID instruction. See PDF.

Oops!

Thanks for your help Mickey, That'll be why it ain't working

I was using a Micrologix1100A processor.

I am trying to creat a PLC program for my group project for a Mechatronics degree in my lunchtime at work. Do you knoe of any way of testing a PLC program without having the actual PLC connected?? or was this my only chance?

Thanks again for taking the time to respond, I will stop the hours of trying to fault find my program now.

Bwengis

Do you knoe of any way of testing a PLC program without having the actual PLC connected??

Click to expand...

That's what RSLogix Emulate 500 is for with its limitation of course.

You could try rolling your own PID. Compare set-point to process, if error is positive ramp a value up, if error is negative ramp a value down. Limit the value to 0-100. Very crude but can work.

Maybe the math gurus will check in and provide a more workable formula.

Thanks again for taking the time to respond, I will stop the hours of trying to fault find my program now.

Click to expand...

In your earlier program, your PID would not have controlled analog Output O:0.0. You put O:0.0 in parallel with the PID block! Instead of that the PID Control Variable Output (CV) N11:4 must be sent (copied or moved) to your analog output. First the PID CV may need to be scaled (using the SCP instrution) to the correct range for the specific analog output.

Read the chapter 19 on PIDs in the "Instruction Set Reference Manual for MicroLogix 1100"