Pid Code Sample - Allen-Bradley Micro830 Manual

Appendix F PID Function Blocks
328

PID Code Sample

The illustration PID Code Sample shows sample code for controlling the PID
application example shown before. Developed using Function Block Diagrams, it
consists of a pre-defined function block, IPIDCONTROLLER, and four use-
defined function blocks. These four are:
• PID_OutputRegulator
This user-defined function block regulates the output of
IPIDCONTROLLER within a safe range to ensure that there is no
damage to the hardware used in the process.
IF RMIN ≤ RIN ≤ RMAX, then ROUT = RIN,
IF RIN < RMIN, then ROUT = RMIN,
IF RIN > RMAX, then ROUT = RMAX.
• PID_Feedback
This user defined function block acts as a multiplexer.
IF "FB_RST" is false, FB_OUT=FB_IN;
If "FB_RST" is true, then FB_OUT=FB_PREVAL.
• PID_PWM
This user defined function block provides a PWM function, converting a
real value to a time related ON/OFF output.
• SIM_WATERLVL
This user defined function block simulates the process depicted in the
application example shown before.
Rockwell Automation Publication 2080-UM002K-EN-E - March 2019