AB PLC 5/40e PID block; max #?

pw3

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• Apr 29, 2008

• #1

Anyone aware if there is a maximum number of PID (PD file type) loops that can be used in the 5/40e?

If someone knows, or if there is a white paper on this someplace, would appreciate it.

Thanks--

 

Mickey

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• Apr 29, 2008

• #2

See pic below and PDF (note 399)
Memory might be a problem with this many.

 

Mickey

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• Apr 29, 2008

• #3

Correction to the above post.
You are actully only limited by the memory
of your processor as you can have multible PD data files ( i.e PD20, PD21
etc.) Each of which can have 399 PD files. But processor memory will surely run out, I'm sure.

 

Last edited: Apr 29, 2008

pw3

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• Apr 30, 2008

• #4

Thanks much for the info--working on a small project involving 40 or so PID's on a 5/40e. Never dealt with that many on one processor and wasn't sure what the usable ceiling was.

 

OkiePC

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• Apr 30, 2008

• #5

The PID instruction processing time for 40 loops will be significant. Read up on the execution time for the instruction and plan your application accordingly.


Paul

 

Gerry

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• Apr 30, 2008

• #6

Another concern is handling all the (presumably) analogue inputs and outputs.
Pay attention to backplane power supply requirements and block transfer update times.