Instruction Manual

Instruction Manual
D103412X012
Detailed Setup—PID Function Block
January 2015
103
α: fixed smoothing factor of 0.1 applied to RATE
F: feedforward control contribution from the feedforward input (FF_VAL)
E: error between setpoint and process variable
To further customize the block for use in your application, you can configure filtering, feedforward inputs, tracking
inputs, setpoint and output limiting, PID equation structures, and block output action. Table 4‐32 lists the PID block
parameters and their descriptions, units of measure, and index numbers, and figure 4‐10 illustrates the internal
components of the PID function block.
Figure 4‐10. PID Function Block Schematic
B2721
FF VAL
Alarm
Detection
Operator
Output
PID
Equation
Setpoint
Limiting
Feedforward
Calculation
BKCAL
OUT
OUT
RCAS
OUT
FF GAIN
FF
SCALE
PV
SCALE
PV
FILTER
SP
HI LIM
SP
LO LIM
SP
RATE DN
SP
RATE UP
Output
Limiting
MODE
BKCAL
IN
TRK
IN D
CAS
IN
IN
TRK
VAL
RCAS
IN
Scaling
and
Filtering
TRK
SCALE
OUT
SCALE
Convert
ROUT
OUT
ROUT
IN
OUT
HI LIM
OUT
LO LIM
OUT
SCALE
HI
HI LIM
HI
LIM
DV
HI LIM
DV
LO LIM
LO
LIM
LO
LO LIM
Operator
Setpoint
GAIN
RATE
RESET