National Instruments 371685C-01

Chapter 2 PID Algorithms

LabWindows/CVI PID Control Toolkit User Manual 2-8 ni.com

Note During tuning, the process remains under closed-loop PID control. It is not

necessary to switch off the existing controller and perform the experiment under open-loop

conditions. In the setpoint relay experiment, the SP signal mirrors the SP for the PID

controller.

Table 2-6. Tuning Formula under PI or PID Control (Slow)

Controller KcTiTd

P0.26Tp/τ— —

PI 0.24Tp/τ5.33τ—

PID 0.32Tp/τ4.0τ0.8τ

Contents

Main Page Important Information Warranty Copyright Trademarks Patents Contents Page About This Manual Conventions Related Documentation Overview of the PID Control Toolkit System Requirements Installation Instructions Activation Instructions PID Control Toolkit Applications PID Control PID Algorithms The PID Algorithm Implementing the PID Algorithm with the PID Functions Error Calculation Proportional Action The Precise PID Algorithm Error Calculation Proportional Action Trapezoidal Integration The Autotuning Algorithm Tuning Formulas Page Page Using the PID Control Toolkit Designing a Control Strategy Setting Timing Tuning Controllers Manually Closed-Loop (Ultimate Gain) Tuning Procedure Open-Loop (Step Test) Tuning Procedure Using the PID Library PID Controller PID Algorithms Control Input Filter Output Rate Limiting Using PID with Autotuning Distributing Applications That Use Wizard-Based Autotuning Using PID with Gain Scheduling Using PID with Lead-Lag Using PID with Setpoint Profiling Using Ramp Generators Converting between Percentage of Full Scale and Engineering Units Using PID on Real-Time (RT) Targets Using PID with DAQ Devices Page A References B Technical Support and Professional Services Page Glossary A B C Page Page O P Page Index A B C D I K L N O S T U W Z