Owner's manual

FOUNDATION
TM
Fieldbus Blocks Manual
A-10
INTEGRATOR (INT)
FUNCTION BLOCK
The Integrator function block is useful for calculating total flow, total
mass, or volume over time. You can also use it to calculate total power,
given the total energy.
Application Example:
Flow Integration
To totalize flow over a one-hour period, configure INTEG_TYPE = 0to?
- periodic reset and configure CLOCK_PER to 3600. Figure A-11
illustrates the correct function block configuration.
Figure A-11. Function Block Diagram
for Row Integration
PROPORTIONAL/
INTEGRAL/DERIVATIVE
(PID) FUNCTION BLOCK
The PID function block is a powerful, flexible control algorithm that is
designed to work in a variety of control strategies. The PID block is
configured differently for different applications. The following examples
describe the use of the PID block for closed-loop control (basic PID loop),
feedforward control, cascade control with master and slave, and
complex cascade control with override.
Closed Loop Control To implement basic closed loop control, compute the error difference
between the process variable (PV) and setpoint (SP) values and
calculate a control output signal using a PID (Proportional Integral
Derivative) function block.
The proportional control function responds immediately and directly to
a change in the PV or SP. The proportional term GAIN applies a change
in the loop output based on the current magnitude of the error
multiplied by a gain value.
The integral control function reduces the process error by moving the
output in the appropriate direction. The integral term RESET applies a
correction based on the magnitude and duration of the error. Set the
RESET parameter to zero for integral-only control. To reduce reset
action, configure the RESET parameter to be a large value.
The derivative term RATE applies a correction based on the anticipated
change in error. Derivative control is typically used in temperature
control where large measurement lags exist.
Process Flow
Measurement
AI
Function
Block
Integrator
Function
Block
OUT
IN_1
FIELDBUS-FBUS_24A