Compact Logix PID Function block

My compact logix processor has 15 temp pid loops but looking in the program there is only one pid function block?

How can this be? Can you run multiple loops off one pid instruction/function block?

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Yes, the only way that can be done is thru subroutines, In this case the way to do it is using input and output parameter every time the subroutine is called, that means that input and output parameters change every time the subroutine is called.
I will never do it this way, main reason is that I prefer to work PID block individually.

Just recently I've seen a similar situation with a PLC5.

The original programmer was using indirect addressing, every scan he/she was moving in the PID variables for each temperature they were controlling.

Scan 1 = Temp 1 Variables, PID did it's thing.
Scan 2 = Temp 2 Variables, PID did it's thing.
Scan 3 = Temp 3 Variables, PID did it's thing.
Scan X = Temp X Variables, PID did it's thing.

Repeat...

Took me a moment to figure that out, might be something similar going on?

I'm assuming it was done like this back when to save processing power/memory?