A5.2 Functions Of Pid Block - YOKOGAWA Admag TI Series User Manual

A5.2 Functions of PID Block
The control calculation processing provided in the PID block has the following functions.
Control Calculation
Processing
PID control
Control output action
Direction of control action
Control action bypass
Feed-forward
Measured-value tracking Equalizes the setpoint (SP) to the measured value (PV).
Setpoint limiter
External-output tracking
Mode change
Bumpless transfer
Initialization and manual
fallback
MAN fallback
Auto fallback
Mode shedding
Block alarm processing
Calculates the control output using the PID control algorithm.
Converts the change in control output (ΔMV) for each control period to the
manipulated value (MV) that is to be actually output.
Supports "velocity type" as an operation of operational output.
Switches the action direction of output between forward and reverse based on the
changes in the deviation.
When the bypass is set, the SP value is scaled to the OUT range and output as
OUT.
Adds the external compensation value FF_VAL to the output signal from the PID
computation.
Limits the value of setpoint (SP) within the high/low limits.
Converts TRK_VAL to the scale of OUT and outputs it.
The PID block has the following eight modes: O/S, IMan, Lo, Man, Auto, Cas, RCas,
and ROut.
Switches the operational output value (OUT) without a sudden change at changing
block modes and switching the operational output value (OUT) at the cascade
downstream block.
Changes MODE_BLK to IMan and temporarily suspends the control action.
Operates when initialization and manual fallback conditions are met.
Changes MODE_BLK to the Man mode and temporarily aborts the control action
forcibly.
Changes MODE_BLK to Auto when MODE_BLK is running in the Cas mode, and
continues the control action using the setpoint set by the operator.
Specifies the block mode with SHED_OPT after a failure.
Supports block alarms, process alarms, and event updates.
<Appendix 5. PID Block>
Description
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IM 01E21A02-03EN