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PID Control Instructions

PID Control Instructions​

  • There is no need to manually write the PIDCAL and PIDINIT instructions since they are automatically created by the PID special program.

  • To write a PID program in the ladder diagram, refer to the below table:

PID Ladder Diagram
TypeInstructionSymbolProcessing InformationCondition
PID InitializationPIDINIT
PIDINIT is used to check the items and to initialize the devices for a PID operation.
PID control data gets assigned from the specified WORD data register, S.
PID CalculationPIDCAL
SV and PV get assigned by the specified data register, S, after the PID calculation.
The result get saved in MV according to the WORD data register, S.
  • Refer to PIDINIT for an expanded PID initialization example in ladder diagram.
  • Refer to PIDCAL for an expanded PID calculation example in ladder diagram.