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Old January 29th, 2004, 09:25 PM   #1
russrmartin
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PID output scaling PLC5

Hello again. I have a question about PID controls. When looking on at a PID control block in a PLC 5, I can see where the input range is scaled from engineering units to the 0-4095 value that the PID block uses. However, I cannot see where the output value is scaled at? Is 4095 a constant in AB PID control variable words, or is there somewhere that one can designate 0-4095, or 32767 to -32767, etc. I'm just trying to get a little better grasp on this. Also, is there anywhere a guy can get a cheat sheet for the abbreviated bits in a PID data table. I don't know know what a DVNA, or a OLH bit stands for. I cannot seem to find a description of what each one is and what it's full name is. Any explanation on this subject is welcome. Thanks.

Russ
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Old January 29th, 2004, 10:45 PM   #2
russrmartin
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New info

Since posting my last thread, I have read in an analog input card manual that the digital resolution is 1 part in 4096 bits. It also shows that the output range is 0 to 4095. This answers most of my question. I didn't think to look at the modules manual. Thanks anyways.

Russ
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Old January 30th, 2004, 05:45 PM   #3
Ron Beaufort
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have you looked here?

the information on the parameter names that you're asking for can be found in:

the PLC-5 Instruction Set Reference Manual

you really need to study all of chapter 14 (PID control) ...

the parameter names you're looking for start on page 14-18 [Adobe Reader page 206 of 372] ...

and to answer your specific question: the PID instruction for the PLC-5 always gives an output which ranges from 0 to 4095 ...
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Last edited by Ron Beaufort; January 30th, 2004 at 05:56 PM.
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