Omron CJ - INSTRUCTIONS Reference Manual page 692

3. Instructions
Hint
• The PIDAT(191) instruction is the same as the PID(190) instruction with the added autotuning (AT)
function, so the PID control operations are identical. Refer to 3-19-1 PID CONTROL: PID(190) for
details on PID control operations and examples.
• PIDAT(191) is executed as if the execution condition was a STOP-RUN signal. PID calculations are
executed when the execution condition remains ON for the next cycle after C+11 to C+40 are
initialized. Therefore, when using the Always ON Flag (ON) as an execution condition for PIDAT(191),
provide a separate process where C+11 to C+40 are initialized when operation is started.
Precautions
• If PIDAT(191) is used between IL(002) and ILC(003), between JMP(004) and JME(005), or in a
subroutine, operation will not be consistent depending on the input condition.
• A PID parameter storage word cannot be shared by multiple PIDAT instructions. Even when the same
parameter is used in multiple PIDAT instructions, separate words must be specified.
• When changing the PID constants manually, set the PID constant change enable setting (bit 1 of
C+5) to 1 so that the values in C+1, C+2, and C+3 are refreshed each sampling period in the PID
calculation. This setting also allows the PID constants to be adjusted manually after autotuning.
• Of the PID parameters (C to C+38), only the following parameters can be changed when the
execution condition is ON. When any other values have been changed, be sure to change the
execution condition from OFF to ON to enable the new settings.
• Set value (SV) in C
(Can be changed during PID control only. An SV change during autotuning will not be
reflected.)
• PID constant change enable setting (bit 1 of C+5)
• P, I, and D constants in C+1, C+2, and C+3
(Changes to these constants will be reflected each sampling period only if the PID constant
change enable setting (bit 1 of C+5) is set to 1.)
• AT Command Bit (bit 15 of C+9)
• AT Calculation Gain (bits 0 to 14 of C+9) and Limit-cycle Hysteresis (C+10) (These values are
read when autotuning starts.)
PID Parameter Settings
Control data Item
C Set value (SV)
C+1 Proportional band
C+2 Tik
Integral Constant
C+3 Tdk
Derivative Constant
C+4 Sampling period ( )
Bits 04 to 15 2-PID parameter ( )
of C+5
Bit 03 of C+5 Manipulated variable
output designation
Bit 01 of C+5 PID constant change
enable setting
654
Contents
The target value of the process being controlled.
The parameter for P action expressing the
proportional control range/total control range.
A constant expressing the strength of the integral
action. As this value increases, the integral
strength decreases.
A constant expressing the strength of the
derivative action. As this value increases, the
derivative strength decreases.
Sets the period for executing the PID action.
The input filter coefficient. Normally use 0.65 (i.e.,
a setting of 000). The filter efficiency decreases
as the coefficient approaches 0.
Designates the manipulated variable output for
when the PV equals the SV.
The timing of enabling changes made to the
proportional band (P), integral constant (Tik), and
derivative constant (Tdk) for use in PID
calculations.
Setting range
Binary data (of the same number of bits as
specified for the input range)
0001 to 270F hex (1 to 9999);
(0.1% to 999.9%, in units of 0.1%)
0001 to 1FFF hex (1 to 8191);
(9999 = Integral operation not executed)
(See note 1.)
0001 to 1FFF hex (1 to 8191);
(0000 = Derivative operation not executed)
(See note 1.)
0001 to 270F hex (1 to 9999);
(0.01 to 99.99 s, in units of 10 ms)
000 hex: = 0.65
Setting from 100 to 163 hex means that the
value of the rightmost two digits is set from
= 0.00 to = 0.99. (See note 2.)
0: Output 0%
1: Output 50%
0: At start of PID instruction execution
1: At start of PID instruction execution and
each sampling period
CS/CJ/NSJ Series Instructions Reference Manual (W474)
Change with ON
input condition
Allowed
Can be changed
with input condition
ON if bit 1 of C+5 is
1.
Not allowed
Allowed