National Instruments FP-3000 - Manual (Page 68)

Chapter 4 Block Reference
FieldPoint FP-3000 User Manual 4-16 www.ni.com
PID Control
In a Fieldbus network, a PID control loop is composed of three function
blocks: an Analog Input (AI) block, a Proportional Integral Derivative
(PID) block, and an Analog Output (AO) block. The PID block’s
IN
parameter is connected to the AI block’s OUT parameter. The PID uses this
linkage to determine the current value of the process variable it is
controlling. The PID uses linkage from the PID’s
OUT parameter to the AO
block CAS_IN parameter to adjust the AO block’s setpoint. To allow the
cascade to be correctly initialized, a third back calculation linkage is
created that allows the AO block to send its current setpoint back up to the
PID block. These linkages are established using configuration software,
such as the NI-FBUS Configurator. For more information, refer to
Example 2: Temperature Control with the FP-3000 in Chapter 3, Example
Applications .
Discrete Input FP-DI-300 Fp Di 300
FP-DI-301 Fp Di 301
FP-DI-330 Fp Di 330
Discrete Output FP-DO-400 Fp Do 400
Fp Cdo 400 (interlock logic)
FP-DO-401 Fp Do 401
Fp Cdo 401 (cold junction)
FP-DO-403 Fp Do 403
Fp Cdo 403
FP-DO-410 Fp Do 410
Fp Cdo 410
FP-RLY 420 Fp Rly 420
Fp Crly 420 (cold junction)
FP-RLY-422 Fp Rly 422
Fp Crly 422
Table 4-6. FieldPoint Modules (Continued)
Channel Type
Supported
Module Block Type