Instruction Manual

Instruction Manual
D103434X012
Blocks
November 2014
89
Feedforward Calculation
The feedforward value (FF_VAL [40]) is scaled (FF_SCALE [41]) to a common range for compatibility with the output
scale (OUT_SCALE [11]). A gain value (FF_GAIN [42]) is applied to achieve the total feedforward contribution.
Output Tracking
Output tracking is enabled through the control options. You can set control options in Manual or Out of Service mode
only.
The Track Enable control option must be set to True for the track function to operate. When the Track in Manual
control option is set to True, the operator cannot override the tracking function in Manual mode. When Track in
Manual is False, the operator can override the tracking function when the block is in Manual mode. Activating the track
function causes the block's actual mode to revert to Local Override.
The TRK_VAL [38] parameter specifies the value to be converted and tracked into the output when the track function
is operating. The TRK_SCALE [37] parameter specifies the range of TRK_VAL [38].
When the TRK_IN_D [38] parameter is True and the Track Enable control option is True, the TRK_VAL [38] input is
converted to the appropriate value and output in units of OUT_SCALE [11].
Set Point Tracking
You can configure the method for tracking the set point by configuring the following control options (CONTROL_OPTS
[12]):
D SP‐PV Track in Man—Permits the SP [8] to track the PV [7] when the actual mode of the block is Man.
D SP‐PV Track in LO or IMan—Permits the SP [8] to track the PV [7] when the actual mode of the block is Local Override
(LO) or Initialization Manual (IMan).
D SP‐PV Track in ROUT—Permits the SP [8] to track the PV [7] when the actual mode of the block is RemoteOut
(ROUT).
D SP Track retained Target—Causes the set point to track the RCAS or CAS parameter based on the retained target
mode when the actual mode is MAN or LO.
D Act On IR—If this option is true, then when IR (Initialization Requested) is received on BKCAL_IN [27], the SP [8] will
be adjusted within setpoint limits to provide bumpless transfer when the cascade is closed. If the setpoint required
to provide bumpless transfer is outside the setpoint limits, then any difference added to provide bumpless transfer
will be removed in the BAL_TIME [25].
When one of these options is set, the SP[8] value is set to the PV [7] value while in the specified mode.
You can select the value that a master controller uses for tracking by configuring the Use PV for BKCAL_OUT control
option. The BKCAL_OUT [31] value tracks the PV value. BKCAL_IN [27] on a master controller connected to
BKCAL_OUT [31] on the PID block in an open cascade strategy forces its OUT [9] to match BKCAL_IN [27], thus
tracking the PV from the slave PID block into its cascade input connection (CAS_IN [18]). If the Use PV for BKCAL_OUT
option is not selected, the working set point (SP_WRK [68]) is used for BKCAL_OUT [31].
You can set control options in Manual or Out of Service mode only. When the mode is set to Auto, the SP [8] will
remain at the last value (it will no longer follow the PV [7].