Yaskawa MP900 Series Ladder Programming Manual User Manual
Page 227
5.8 DDC Instructions
5.8.6 PID Control (PID)
5-158
[ b ] Parameter Table Configuration for PID Instruction with Real Numbers
∗ The relay input and output bit assignments are the same as for integers.
[ c ] Internal Operation of the Instruction
The deviation X input is used to calculate the PID compensation output as shown below.
In the formula shown below, X’ is the previous input value of X, Y’ is the previous I compensation, Ts is the scan time
set value, and Td* is the differential time.
∗ The differential time (Td) is Td1 when X – X’ and X’ have the same sign, and Td2 when X – X’ and X’ have dif-
ferent signs.
When IRST (reset integration) is closed, the PID compensation is calculated with the I compensation set to 0.
P compensation = Upper/lower limit (UL or LL) of (Kp
× X)
Yi (I compensation) = Upper/lower limit (IUL or ILL) of { (Ki
× X + IREM) /
+ Yi’}
D compensation = Kd
× (X – X’) × Upper/lower limit (IUL or ILL) of
Y (PID compensation) = Upper/lower limits (UL or LL) of P + I + D compensation values and dead zone A
(Width DB)
Address
Data
Type
Symbol
Name
Specification
I/O
0
W
RLY
Relay I/O
Relay inputs and relay outputs
*
IN/OUT
1
W
–
(Reserved.)
Spare register
IN
2
F
Kp
P gain
Gain for the P compensation
IN
4
F
Ki
I gain
Gain for the input to the integral circuit
IN
6
F
Kd
D gain
Gain for the input to the differential circuit
IN
8
F
Ti
Integral time
Integral time (s)
IN
10
F
Td1
Differential time for
divergence
Differential time used when the input diverges (s)
IN
12
F
Td2
Differential time for
convergence
Differential time used when the input converges (s)
IN
14
F
IUL
Upper integration
limit
Upper limit for the I compensation
IN
16
F
ILL
Lower integration
limit
Lower limit for the I compensation
IN
18
F
UL
PID upper limit
Upper limit for the P + I + D compensation
IN
20
F
LL
PID lower limit
Lower limit for the P + I + D compensation
IN
22
F
DB
PID output dead zone
Dead zone width for the P + I + D compensation
IN
24
F
Y
PID output
PID compensation output (output to Out)
OUT
26
F
Yi
I compensation
I compensation storage
OUT
28
F
X
Input value storage
Storage of current input value
OUT
Ti
Ts
Td
Ts