<Appendix 5. PID Block>
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IM 01E21A02-03EN
A5.13 Measured-value Tracking
Measured-value tracking is an action to equalize the setpoint (SP) to the measured value (PV)
when the block mode (MODE_BLK) is running in Man in order to prevent a sudden change in
control output from being caused by a mode change to Auto.
If the mode of the cascade secondary loop is changed from the Cas mode to the Auto mode
while the cascade primary loop is controlling in the Auto or Cas mode, the cascade connection is
opened and the control action of the primary loop stops. The setpoint (SP) of the secondary loop
can also be equalized to its cascade input (CAS_IN) by tracing the measured value.
The settings for measured-value tracking are made in the parameter CONTROL_OPTS.
A5.13.1 CONTROL_OPTS
Setting contents of CONTROL_OPTS are shown.
Selection item for
CONTROL_OPT
Operation Contents
Bypass Enable
This parameter allows BYPASS to be changed.
SP-PV Track in Man
Equalizes SP to PV when MODE_BLK.target is set to the Man mode.
SP-PV Track in ROut
Equalizes SP to PV when the ROut mode is specified with MODE_BLK.target.
SP-PV Track in LO or IMan Equalizes SP to PV when Actual is the LO mode or the IMan mode.
SP Track retained Target
Equalizes SP to RCAS_IN when RCas bit is set in the target mode, and to CAS_
IN when Cas bit is set when the actual mode is IMan, LO, Man and ROut.
Direct Acting
Set the PID block to a direct acting controller.
Track Enable
Transitions to LO if TRK_IN_D becomes 1 with this option being set.
Track in Manual
With the previously mentioned Track Enable alone, this is not valid when the
target mode is Man. Sets this option even in Man when the user would like to
transition to LO. Even if this option is set while Track Enable is not set, there is no
effect.
Use PV for BKCAL_OUT
Sets the value of PV in BKCAL_OUT and RCAS_OUT, instead of the value of SP.
Obey SP limits if Cas or
RCas
Puts the setpoint high/low limits in force in the Cas or RCas mode.
No OUT limits in Manual
Disables the high/low limits for OUT in the Man mode.