Справочник Пользователя для National Instruments FP-3000
Chapter 4
Block Reference
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National Instruments Corporation
4-5
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. Figure 4-1 shows all three
blocks and the interconnections between the blocks. The PID block’s
blocks: an Analog Input (AI) block, a Proportional Integral Derivative
(PID) block, and an Analog Output (AO) block. Figure 4-1 shows all three
blocks and the interconnections between the blocks. 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
controlling. The PID uses linkage from the PID’s
OUT
parameter to the AO
block
CAS_IN
parameter to adjust the AO block 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 must be established by using a PC-based
Fieldbus configuration system, such as the NI-FBUS Configurator. For
more information, refer to
created that allows the AO block to send its current setpoint back up to the
PID block. These linkages must be established by using a PC-based
Fieldbus configuration system, such as the NI-FBUS Configurator. For
more information, refer to
.
Table 4-2. Function Blocks and FieldPoint Modules
Channel Type
Supported
Module
Block Type
Analog Input
FP-AI-100
Fp Ai 100
FP-AI-110
Fp Ai 110
FP-AI-111
Ap Ai 111
FP-TC-120
Fp Tc 120, Fp Tc 120 C
FP-RTD-122
Fp Rtd 122
Analog Output
FP-AO-200
Fp Ao 200
FP-PWM-520
Fp Pwm 520
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
FP-DO-401
Fp Do 401, Fp Cdo 401
FP-RLY 420
Fp Rly 420, Fp Crly 420