7.9 Proportional/integral/derivative (PID) function
block
The PID function block combines all of the necessary logic to perform proportional/
integral/derivative (PID) control. The block supports mode control, signal scaling and
limiting, feedforward control, override tracking, alarm limit detection, and signal status
propagation.
Proportional/integral/derivative (PID) function blockFigure 7-12:
• BKCAL_IN = The analog input value and status from another block's BKCAL_OUT output that is
used for backward output tracking for bumpless transfer and to pass limit status.
• CAS_IN = The remote setpoint value from another function block.
• FF_VAL = The feedfoward control input value and status.
• IN = The connection for the process variable from another function block.
• TRK_IN_D = Initiates the external tracking function.
• TRK_VAL = The value after scaling applied to OUT in Local Override mode.
• BKCAL_OUT = The value and status required by the BKCAL_IN input of another function block to
prevent reset windup and to provide bumpless transfer to closed loop control.
• OUT = The block output and status.
The block supports two forms of the PID equation: Standard and Series. You can choose
the appropriate equation using the FORM parameter. The standard ISA PID equation is the
default selection.
Foundation Fieldbus
Reference Manual 149
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