Chapter 7. PID Built-In Function BlockGFK-2950C February 2018 3477.2.2 Reference Array ParametersNote: Machine Edition software allows you to modify the configurable parameters for a PIDinstruction in real time in online programmer mode. To customize PID parameters, right clickthe PID function and select Tuning.Words Parameter/Description Low BitUnits Range1(Address+0)Loop NumberOptional number of the PID block. It provides a common identificationin the CPU with the loop number defined by an operator interfacedevice.Integer 0 to 255 (foruser displayonly)2(Address+1)Algorithm1 = ISA algorithm2 = Independent algorithm- Set by the CPU3(Address+2)Sample PeriodThe shortest time, in 10ms. Increments, between solutions of the PIDalgorithm. For example, use a 10 for a 100ms. Sample period.Minimum time of 10ms is enforced by the block if the sweep<10ms)10ms. 0 (everysweep) to65535(10.9 Min) Atleast 10ms.4,5(Address+3,Address+4)Dead Band +Dead Band –Integral values defining the upper (+) and lower (-) Dead Band limits. Ifno Dead Band is required, these values must be 0. If the PID Error (SP -PV) or (PV - SP) is above the (-) value and below the (+) value, the PIDcalculations are solved with an Error of 0. If non-zero, the (+) valuemust greater than 0 and the (-) value less than 0 or the PID block willnot function.Leave these at 0 until the PID loop gains are set up or tuned. A DeadBand might be added to avoid small CV output changes due tovariations in error.PVCountsDead Band +: 0to 32767(nevernegative)Dead Band -: -32768 to 0(neverpositive)6(Address+5)PID_IND: Proportional Gain (Kp)PID_ISA: Controller gain (Kc = Kp)PID_IND: Change in the control variable in CV Counts for a 100 PVCount change in the Error term. Entered as an integer representing afixed-point decimal ratio with two decimal places. Displayed as a ratioof percentages with two decimal places.For example, a Kp entered as 450 is displayed as 4.50 and results in aKp * Error / 100 or 450 * Error / 100 contribution to the PID Output.PID_ISA: Same as PID_IND.Kp is generally the first gain set when adjusting a PID loop.33 CV%/PV%%CV/%PV0 to 327.67%
