Rockwell Automation Publication 1756-RM003N-EN-P - October 2011 517
Special Instructions (FBC, DDT, DTR, PID) Chapter 13
Specify Configuration
Select the Configuration tab. You must click OK or Apply for any changes to
take effect.
Specify Alarms
Select the Alarms tab. You must click OK or Apply for any changes to
take effect.
In this field Specify
PID equation Select independent gains or dependent gains (.PE).
Use independent when you want the three gains (P, I, and D) to operate independently. Use
dependent when you want an overall controller gain that affects all three terms (P, I, and D).
Control action Select either E=PV-SP or E=SP-PV for the control action (.CA).
Derivative of Select PV or error (.DOE).
Use the derivative of PV to eliminate output spikes resulting from setpoint changes. Use the
derivative of error for fast responses to setpoint changes when the algorithm can tolerate
overshoots.
Loop update time Enter the update time (.UPD) for the instruction.
CV high limit Enter a high limit for the control variable (.MAXO).
(1)
CV low limit Enter a low limit for the control variable (.MINO).
(1)
Deadband value Enter a deadband value (.DB).
No derivative smoothing Enable or disable this selection (.NDF).
No bias calculation Enable or disable this selection (.NOBC).
No zero crossing in deadband Enable or disable this selection (.NOZC).
PV tracking Enable or disable this selection (.PVT).
Cascade loop Enable or disable this selection (.CL).
Cascade type If cascade loop is enabled, select either slave or master (.CT).
(1) When using the ladder-based PID instruction, if you set MAXO = MINO, the PID instruction will reset these values
to default. MAXO = 100.0 and MINO = 0.0
In this field Specify
PV high Enter a PV high alarm value (.PVH).
PV low Enter a PV low alarm value (.PVL).
PV deadband Enter a PV alarm deadband value (.PVDB).
Positive deviation Enter a positive deviation value (.DVP).
Negative deviation Enter a negative deviation value (.DVN).
Deviation deadband Enter a deviation alarm deadband value (.DVDB).
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