National Instruments 371685C-01 用户手册

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Currently, the PID algorithm is the most common control algorithm used in industry. Often, 
PID is used to control processes that include heating and cooling systems, fluid level 
monitoring, flow control, and pressure control. When using PID control, you must specify a 
process variable and a setpoint. The process variable is the system parameter you want to 
control, such as temperature, pressure, or flow rate. The setpoint is the desired value for the 
parameter you are controlling. A PID controller determines a controller output value, such as 
the heater power or valve position. When applied to the system, the controller output value 
drives the process variable toward the setpoint value.

You can use the PID Control Toolkit functions with National Instruments hardware to develop 
LabWindows/CVI control applications. Use I/O hardware, such as DAQ devices, FieldPoint 
I/O modules, or GPIB boards, to connect your PC to the system you want to control. You can 
use the LabWindows/CVI I/O functions with the PID Control Toolkit to develop a control 
application or modify the examples provided with the toolkit.

Using the PID Control Toolkit functions, you can develop the following control applications 
based on PID controllers:

•

Proportional (P), proportional-integral (PI), proportional-derivative (PD), and 
proportional-integral-derivative (PID) algorithms

•

Gain-scheduled PID

•

PID autotuning

•

Precise PID

•

Lead-lag compensation

•

Setpoint profile generation

•

Multiloop cascade control

•

Feedforward control

•

Override (minimum/maximum selector) control

•

Ratio/bias control

Refer to the LabWindows/CVI PID Control Toolkit Help, which you can access by selecting 
Start»All Programs»National Instruments»PID Control Toolkit for CVI»LabWindows 
CVI PID Help, for more information about the functions.