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MELSEC-L PID Control (Function block difference / limit)


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Posted (edited)

Hello. I will be very grateful for your help!


There is a MELSEC-L controller (GX Works2), it is necessary to implement PID controllers.

Question:
Is it possible to work with 33 or more PID controllers at the same time?

Why I have this question:
1) There is a 
dl.mitsubishielectric.com : MELSEC-Q/L/QnA Programming Manual (PID Control Instructions)
On page №16, there is a table that says "Number of PID control loops: 32 loops (maximum)".

2) In the

dl.mitsubishielectric.com : MELSEC-Q/L Programming Manual (Common Instruction)

On page №737, there is a description of the "PID" function block, where there is no limit on the number of uses. I saw a note about the CPU serial number.

3) On the Mitsubishi website there is a library fb-cpu-pid_v110l_e.zip
www.mitsubishielectric.co.jp : fb-cpu-pid_v110l_e.zip

I can't figure out if there's a limit to how many PID controllers can work at the same time in a program. What is the difference between PID controllers (from the points above)?

p.s. I liked the pid regulator from point №2 the most.

Edited by Neverov
Posted

I have made my own PID for Q series, and I have used it for more than 50 PIDs simultaneously. The processes were not to fast (mostly 100ms sampling).

If you make your ow function, at the end it will all depend of CPU processing power. With L26 it should be easy to do it, with  L02 I don't believe it is possible, with L06 depending of memory capacity other already used for other function (very likely you can do it).

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