Omron SYSMAC CJ - REFERENCE MANUAL 08-2008 Reference Manual page 807

Data Control Instructions
Direction of Action
Derivative Action
Step response
Deviation
0
Manipulated
0
variable
PD Action and Derivative Time
Ramp response
Deviation
0
Manipulated
variable 0
Td: Derivative time
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.
Step Response of PID Control Action Output
Step response
Deviation
0
Manipulated
0
variable
Ramp Response of PID Control Action Output
Ramp response
Deviation
0
Manipulated
0
variable
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.
Section 3-18
PD action
P action
D action
PID action
I action
P action
D action
PID action
I action
P action
D action
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