Omron CP - PROGRAMMING MANUAL 05-2007 - Page 665

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Data Control Instructions Section 3-17
If the actual sampling period is more than twice the designated sampling
period, an error will occur and the Error Flag will turn ON. PID control will still
be executed, however.
The Carry Flag turns ON while PID control is being executed.
The Greater Than Flag turns ON if the manipulated variable after the PID
action exceeds the upper limit. At this time, the results are output at the upper
limit.
The Less Than Flag turns ON if the manipulated variable after the PID action
is below the lower limit. At this time, the results are output at the lower limit.
PID Parameter Settings
Control
data
Item Contents Setting range Change with
ON input
condition
C Set value (SV) The target value of the process
being controlled.
Binary data (of the same number
of bits as specified for the input
range)
Allowed
C+1 Proportional band The parameter for P action
expressing the proportional con-
trol range/total control range.
0001 to 270F hex (1 to 9999);
(0.1% to 999.9%, in units of
0.1%)
Can be
changed with
input condition
ON if bit 1 of
C+5 is 1.
C+2 Tik
Integral Constant
A constant expressing the
strength of the integral action. As
this value increases, the integral
strength decreases.
0001 to 1FFF hex (1 to 8191);
(9999 = Integral operation not
executed) (See note 1.)
C+3 Tdk
Derivative Constant
A constant expressing the
strength of the derivative action.
As this value increases, the
derivative strength decreases.
0001 to 1FFF hex (1 to 8191);
(0000 = Derivative operation not
executed) (See note 1.)
C+4 Sampling period (τ) Sets the period for executing the
PID action.
0001 to 270F hex (1 to 9999);
(0.01 to 99.99 s, in units of
10 ms)
Not allowed
Bits 04 to 15
of C+5
2-PID parameter (α) The input filter coefficient. Nor-
mally use 0.65 (i.e., a setting of
000). The filter efficiency
decreases as the coefficient
approaches 0.
000 hex: α = 0.65
Setting from 100 to 163 hex
means that the value of the right-
most two digits is set from α=
0.00 to α= 0.99. (See note 2.)
Bit 03 of C+5 Manipulated vari-
able output designa-
tion
Designates the manipulated vari-
able output for when the PV
equals the SV.
0: Output 0%
1: Output 50%
Bit 01 of C+5 PID constant
change enable set-
ting
The timing of enabling changes
made to the proportional band
(P), integral constant (Tik), and
derivative constant (Tdk) for use
in PID calculations.
0: At start of PID instruction exe-
cution
1: At start of PID instruction exe-
cution and each sampling period
Allowed