Endress+Hauser PROline Prosonic Flow 93 Function Manual page 191

PROline Prosonic Flow 93 FOUNDATION Fieldbus
Endress+Hauser
6 PID function block (PID controller)
A PID function block contains the input channel processing, the proportional integral-
differential control (PID) and the analog output channel processing. The configuration
of the PID function block depends on the automation task. The following can be
realised: basic closed-control loops, feedforward control, cascade control, cascade
control with limiting.
The possibilities available for data processing within the PID function block include:
signal scaling and limiting, operating mode control, feedforward control, limiting control,
alarm detection, signal status propagation.
• IN = Input of the controlled variable from another function block.
• CAS_IN = Input of the remote setpoint value from another function block.
• BKCAL_IN = Input of the feedback value and status from the BKCAL_OUT output of the downstream
function block which ensures bumpless switching of the operating mode.
• TRK_IN_D = Discrete input for activating the external output tracking function.
• TRK_VAL = Input for the external value for tracking from another function block.
• FF_VAL = Input for the disturbance variable from another function block.
• OUT = Output value and status (manipulated variable) of the PID function block.
• BKCAL_OUT = Output for the feedback value and status transferred to the BKCAL_IN input of the
upstream function block to ensure bumpless switching of the operating mode.
6.1 Signal processing
PID Block
FF_VAL
Setpoint from super-
visory host system
RCAS_IN
CAS_IN
SP
TRK_IN_D
MODE
BKCAL_IN
Scaling and PV
IN
filtering
PV_SCALE
PV_FILTER
TRK_VAL
Fig. 5: Internal structure of the PID function block
6 PID function block (PID controller)
Feed forward
calculation
FF_GAIN
FF_SCALE
RCAS_OUT
Bypass
Setpoint PID
limiting Equation
SP_HI_LIM
GAIN
SP_LO_LIM
RATE
SP_RATE_DN
RESET
SP_RATE_UP
Alarm
detection
HI_HI_LIM / HI_LIM
TRK_SCALE
LO_LO_LIM / LO_LIM
OUT_SCALE
DV_HI_LIM / DV_LO_LIM
Converter
Output from super-
visory host system
ROUT_IN ROUT_OUT
Output
limiting
Calculated
actuating
variable
OUT_HI_LIM
OUT_LO_LIM
OUT_SCALE
BCAL_OUT
OUT
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