Chapter 20 Proportional Integral Derivative (PID) instruction
586 Rockwell Automation Publication 2080-RM001D-EN-E - February 2015
Function blocks and UDFBs used in the water level FBD
This application, developed in the Function Block Diagram (FBD) language, uses
the function blocks described in the following table.
Function block Description
IPIDController function block Provides PID process control
PID_OutputRegulator UDFB Regulates the output of the IPIDCONTROLLER within a safe range to ensure the hardware used in the process is not
damaged
Sample code:
IF RMIN ≤ RIN ≤ RMAX, then ROUT = RIN,
IF RIN < RMIN, then ROUT = RMIN,
IF RIN > RMAX, then ROUT = RMAX
PID_Feedback UDFB Acts as a multiplexer
Sample code:
IF "FB_RST" is false, FB_OUT=FB_IN;
If "FB_RST" is true, then FB_OUT=FB_PREVAL.
PID_PWM UDFB Provides a PWM function, converting a real value to a time related ON/OFF output
SIM_WATERLVL UDFB Simulates the process in the application example
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