[Instruction] Contents

Advanced Function InstructionFUN 30PIDGENERAL PURPOSE PID OPERATION(Brief description)FUN 30PIDTs : PID Operation time intervalSR : Starting register of process controlparameter table comprised by 8 consecutiveregisters.OR : PID output registerPR : Starting register of the process parametertable comprised by 7 consecutive registers.OperandRangeHR ROR DR KR0∣R3839R5000∣R8071D0∣D4095Ts ○ ○ ○ 1~3000SR ○ ○* ○OR ○ ○* ○PR ○ ○* ○WR ○ ○* ○WR : Starting register of working variable for PIDinternal operation. It requires 7 registers andcan’t be re-used in other part of the ladderprogram.• PID function according to the current value of process variable (PV) derived from the external analog signaland the setting value (SP) of process performs the calculation, which base on the PID formula. The result ofcalculation is the control output for the controlled process, which can feed directly to the AO module or otheroutput interface or leaved for further process. The usage of PID control for process if properly can achieve afast and smooth result of PV tracking toward SP change or immune to the disturbance of process.• The PID formula in digital form:Mn =n[(D4005/Pb)×En]+ ∑0[(D4005/Pb)×Ti×Ts×En] − [(D4005/Pb)×Td×(PVn−PVn-1)/Ts] + BiasMn : Control output at time ”n”Pb : Proportional band ( range : 2~5000, unit 0.1%. Kc (gain) =1000/ Pb )Ti : Intergal time constant ( range : 0~9999 corresponds to 0.00~99.99 Repeats/Minute )Td : Differential time constant ( range : 0~9999 corresponds to 0.00~99.99 Minutes )PVn : Process value at time ”n”PV n-1 : Process value at time ”n”En :Error at time ”n” =set value ( SP) − process value at time ”n” (PVn)Ts : Interval time of PID calculation ( range: 1~3000, unit : 0.01 S )Bias : Control output offset ( range: 0~16380 )• For detail description of this function, please refer chapter 20.7-9