KH 8384-5 EN
23
Block model
−
Derivative component:
In controlled systems with long delay times, e.g. in temperature control loops, it is better
to use the derivative component RATE of the controller. Using the derivative component
RATE, the output variable is calculated depending on the rate of change of the set point
deviation.
An OUT value is generated from the calculated ouput value based on the OUT_SCALE,
OUT_HI_LIM and OUT_LO_LIM parameters. It can be forwarded to a downstream function
block.
The status of the OUT value can be influenced by the STATUS_OPTS parameter depending
on the status of the input variables of the PID Function Block. As a result, the fault state of a
following output block can be activated, for example.
The BYPASS parameter allows the internal set point to pass directly through to the output val
-
ue. The FF_VAL input value allows feedforward control, while TRK_IN_D and TRK_VAL allow
the direct tracking of the out value.
See page 99 for parameter list.
IO_OPTS
Inverted
OUT_D
SP_D
CAS_IN_D
RCAS_IN_D
MAN
MODE_BLK
Fault State
FSTATE_TIME
FSTATE_VALVUE_D
MODE_BLK
Simulate
SIMULATE_D
OUT_D
SELECT_DO1
READBACK_D
IO_OPTS
Inverted
PV_D
Open/close application
1)
Start VST (Valve Stroke Test)
Reset diagnosis
Reset message logger
Set to fail-safe position
Start data logger
Set local op. write protection
Reset/stop diagnosis
1)
Only supports DO1 Function
Block
Fig. 3:
Proportional Integral Derivative Function Block (PID)