Compact Logix PID

How Many pid loops is a compact logix processor good for?

I do not have my specific model info at the moment but what i mean is do you guy's typically use them to the max that they support?

I Have been told that using the max amount of loops is very hard on the processor and worse with other logic running and the accuracy and speed of some or all loops suffer.

Is this true? What is a good limit to leave unused and add an additional processor in general?

bump

As many as memory and scan time permits. There are no other hardware limits.

I don't know about the effect of scan time, running the max, as one CompactLogix could probably support every single PID used in this plant, but that would be silly.

What model CompactLogix?

The document (included in your RSLogix Installation folder) "Execution_Time_And_Memory.pdf" lists the worst case execution time for a PID on a CompactLogix as 530.0 microseconds, on an L30, running ISA Independent mode.