Publication 1762-RM001C-EN-P
19-18 Process Control Instruction
Application Notes
The following paragraphs discuss:
•
Input/Output Ranges
•
Scaling to Engineering Units
•
Zero-crossing Deadband
•
Output Alarms
•
Output Limiting with Anti-reset Windup
•
The Manual Mode
•
Feed Forward
Input/Output Ranges
The input module measuring the process variable (PV) must have a full
scale binary range of 0 to 16383. If this value is less than 0 (bit 15 set),
then a value of zero is used for PV and the “Process var out of range” bit
is set (bit 12 of word 0 in the control block). If the process variable is
greater than 16383 (bit 14 set), then a value of 16383 is used for PV and
the “Process var out of range” bit is set.
The Control Variable, calculated by the PID instruction, has the same
range of 0 to 16383. The Control Output (word 16 of the control block)
has the range of 0 to 100%. You can set lower and upper limits for the
instruction’s calculated output values (where an upper limit of 100%
corresponds to a Control Variable limit of 16383).
ATTENTION
!
Do not alter the state of any PID control block value
unless you fully understand its function and how it will
affect your process. Unexpected operation could result
with possible equipment damage and/or personal injury.
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