LS Industrial Systems SV-iS7 PLC User Manual

Chapter 6 Usage of Various Functions
6-13
3) Realization of PID control on the PLC option card
In this chapter, it will describe how to get the digitized formula of the P, I, and D terms.
(a) P control
The digitized formula of P control is as following;
[] )()()( nPVnSVKnP −=
n : sampling number K : proportional gain constant
b : reference value SV : set value
PV : present value
(b) I control
The continuous formula of I control is as following;
∫
=
t
i
dsse
T
K
tI
0
)()(
: integral term
K : proportional gain constant
Ti : integral time
e(s) : deviation value
By derivation about t, we can obtain;
e
Ti
K
dt
dI
= where, e = (SV – PV) : deviation value
The digitized formula is as following;
)(
)()1(
ne
Ti
K
h
nInI
=
−+
where, h : sampling period
)()()1( ne
Ti
Kh
nInI +=+
(c) D control
The continuous formula of derivative term is as following;
dt
dy
KTdDD
dt
d
N
Td
−=+×
N : high frequency noise depression ration
y : the object to be controlled (PV)

LS Industrial Systems SV-iS7 PLC Specifications

General

Brand	LS Industrial Systems
Model	SV-iS7 PLC
Category	Computer Hardware
Language	English