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Data Control Instructions Section 3-18
PID Action
PID action combines proportional action (P), integral action (I), and derivative
action (D). It produces superior control results even for control objects with
dead time. It employs proportional action to provide smooth control without
hunting, integral action to automatically correct any offset, and derivative
action to speed up the response to disturbances.
Direction of Action When using PID control, select either of the following two control directions. In
either direction, the MV increases as the difference between the SV and the
PV increases.
• Forward action: MV is increased when the PV is larger than the SV.
• Reverse action: MV is increased when the PV is smaller than the SV.
0
0
0
0
Ramp response
Step response
PD action
P action
D action
Td: Derivative time
Manipulated
variable
Deviation
Manipulated
variable
Deviation
Derivative Action
PD Action and Derivative Time
0
0
0
0
PID action
I action
P action
D action
Step response
PID action
I action
P action
D action
Ramp response
Manipulated
variable
Manipulated
variable
Step Response of PID Control Action Output
Ramp Response of PID Control Action Output
Deviation
Deviation
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