Delta AS Series Programming Manual page 488

interval between the timed interrupt tasks. The PID algorithm is applied according to the interval between the timed
interrupt tasks.
5. Before the 32-bit PID algorithm is applied, the process value used in the PID instruction has to be a stable value.
When you need the input value in the module to implement the DPID algorithm, must note the time it takes for the
analog input to be converted into the digital input.
6. When the PV (process value) is in the range of ERR_DBW, at the beginning, the present error is brought into the
PID algorithm according to the normal processing, and then the CPU module checks whether the present error
meets the cross status condition: PV (process value) goes beyond the SV (target value). Once the condition is met,
the present error is counted as 0 when applying the PID algorithm. After the PV (process value) is out of the
ERR_DBW range, the present error is brought into the PID algorithm again. If PID_DE is true, that means it uses
the variations in the PV to calculate the control value of the derivative, and after the cross status condition is met,
the PLC treats Δ PV as 0 to apply the PID algorithm. (Δ PV= current PV – previous PV). In the following example,
the present error is brought into the PID algorithm according to the normal processing in section A ,and the present
error or Δ PV is counted as 0 to apply the PID algorithm in the section B.
The PID algorithm:
1. When you set PID_MODE to 0, the PID control mode is the automatic control mode.

Independent Formula & Derivative of E（PID_EQ=False & PID_DE=False）
MV K E Ki
= +
P

Independent Formula & Derivative of PV（PID_EQ=False & PID_DE=True）
MV = K E + Ki
P
MV = K E + Ki
P

Dependent Formula & Derivative of E（PID_EQ=True & PID_DE=False）

1
MV K E
= +

c
T


Dependent Formula & Derivative of PV（PID_EQ=True & PID_DE=True）
t
dE
∫
E = SV – PV or E = PV – SV
E dt K * BIAS
+ +
d
dt
0
t
dPV
∫
*
E dt − K + BIAS
d
dt
0
Or
t
dPV
∫
*
E dt + K + BIAS
d
dt
0

t
dE
∫
E dt T * BIAS
+ +

d
dt

i
0
Ch ap te r 6 Ap pl ie d Instruc ti ons
E = SV – PV
E =PV – SV
E = SV – PV or E = PV – SV
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