Mitsubishi Electric MELSEC iQ-R Series Programming Manual page 241

• PIDP operations are conducted as follows.
Item
Deviation (DVn)
Output variation (MV)
In
Bn
Kp: Gain
Ti: Integral time
Td: Derivative time
Md: Derivative gain
CT: Control cycle
DVn: Deviation
DVn-1: Last deviation value
PVn: Process variable
PVn-1: Last process variable
SVn: Engineering value conversion processing result
The integral term and derivative term are as follows under the following conditions.
Item Condition
Derivative When Td = 0
term
When the control mode is MAN
When the control mode is CMV
Integral When Ti = 0
term
When an MH error has occurred and the following expression is
satisfied
CT
×DVn>0
Ti
When an ML error has occurred and the following expression is
satisfied
CT
×DVn<0
Ti
Ti: Integral time
CT: Control cycle
DVn: Deviation
MH: Output high limit value
ML: Output low limit value
Set an integral multiple of the execution cycle (T) as a control cycle (CT).
Set 0.0 or a value equal to or larger than the control cycle (CT) as an integral constant.
PIDP operations of this tag access FB are performed every control cycle (CT) (MV output).
In other execution cycles (T), the last manipulated value is held.
10.10 Position Type PID Control (Disable Tracking for primary loop/Disable Tracking from secondary loop) (M+P_PIDP)
Direct action
DVn = PVn - SVn
MV = Kp × { DV + I + B }
n n n
Derivative
Integral
Proportional
Gain
CT
I =I + ×DV
n n-1 n
Ti
Md×Td
×
B =B +
n n-1
Md×CT+Td
CT×B
n-1
{(PV -PV )-
}
n n-1
Td
Processing
Bn = 0
CT
Ti
Reverse action
DVn = SVn - PVn
Md×Td
B =B +
n n-1
Md×CT+Td
{-(PV -PV
n n-1
×DV =0
n
10 LOOP CONTROL OPERATION
10
×
CT×B
n-1
)-
}
Td
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