Publication 1763-RM001C-EN-P - October 2009
288 Process Control Instruction
Control Variable Percent (CVP)
CVP (Control Variable Percent) displays the control variable as a
percentage. The range is 0 to 100%.
If the PD10:0/AM bit is off (automatic mode), CVP tracks the control
variable (CV) output being calculated by the PID equation.
If the PD10:0/AM bit is on (manual mode), CVP tracks the value that can
be manipulated in the Control Variable (CV) data word.
The only way for a programmer to have control of the PID CV is to place
the PID instruction in manual mode and write to the CV word via the
control program or programming software. If no change is made to CV
while in manual mode, the CVP will display the last value calculated by
the PID equation.
Scaled Process Variable (SPV)
The SPV (Scaled Process Variable) is the analog input variable. If scaling is
enabled, the range is the minimum scaled value (MinS) to maximum
scaled value (MaxS).
If the SPV is configured to be read in engineering units, then this
parameter corresponds to the value of the process variable in engineering
units. See Analog I/O Scaling on page 299 for more information on
scaling.
Output Parameter
Descriptions
Address Data
Format
Range Type User Program
Access
CVP - Control Variable Percent PD10:0.CVP word (INT) 0 to 100 control status read
Input Parameter
Descriptions
Address Data
Format
Range Type User Program
Access
SPV - Scaled Process Variable PD10:0.SPV word (INT) 0 to 16383 status read only
efesotomasyon.com - Allen Bradley,Rockwell,plc,servo,drive
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