National Instruments PID Control Toolkit 371685C-01 User Manual

National Instruments PID Control Toolkit 371685C-01 User Manual Manual pdf 9 page image

Chapter 1 Overview of the PID Control Toolkit© National Instruments Corporation 1-3 LabWindows/CVI PID Control Toolkit User ManualPID ControlCurrently, 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 levelmonitoring, flow control, and pressure control. When using PID control, you must specify aprocess variable and a setpoint. The process variable is the system parameter you want tocontrol, such as temperature, pressure, or flow rate. The setpoint is the desired value for theparameter you are controlling. A PID controller determines a controller output value, such asthe heater power or valve position. When applied to the system, the controller output valuedrives the process variable toward the setpoint value.You can use the PID Control Toolkit functions with National Instruments hardware to developLabWindows/CVI control applications. Use I/O hardware, such as DAQ devices, FieldPointI/O modules, or GPIB boards, to connect your PC to the system you want to control. You canuse the LabWindows/CVI I/O functions with the PID Control Toolkit to develop a controlapplication or modify the examples provided with the toolkit.Using the PID Control Toolkit functions, you can develop the following control applicationsbased on PID controllers:• Proportional (P), proportional-integral (PI), proportional-derivative (PD), andproportional-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 controlRefer to the LabWindows/CVI PID Control Toolkit Help, which you can access by selectingStart»All Programs»National Instruments»PID Control Toolkit for CVI»LabWindowsCVI PID Help, for more information about the functions.