Omron CJ - REFERENCE MANUAL 02-2010 Reference Manual page 684

3. Instructions
Precautions
• If PID(190) 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.
• Within the PID parameters (C to C+38), the only value that can be changed while the input condition
is ON is the set value for C. If any other value is changed, be sure to turn the input condition from
OFF to ON to enable the new value.
• PID(190) 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+9 to C+38 are
initialized. Therefore, when using the Always ON Flag (ON) as an execution condition for PID(190),
provide a separate process where C+9 to C+38 are initialized when operation is started.
• A PID parameter storage word cannot be shared by multiple PID instructions. Even when the same
parameter is used in multiple PID instructions, separate words must be specified.
Example Programming
0.00
10
D200
20
Parameters
PV: word
10 PID control
Manipulated variable output:
CIO 20
Note When CIO 0.00 is OFF, operation can be the same as manual operation by writing to CIO 20.
When changing from manual operation to automatic operation by executing PID(190), extreme changes in
the manipulated value are restricted. (The manipulated variable after switching to automatic operation will
start at the previous value of the integral manipulated variable.)
648
• At the rising edge of CIO 0.00 (OFF to ON), the work area in D209 to D238
is initialized according to the parameters (shown below) set in D200 to
D208. After the work area has been initialized, PID control is executed and
the manipulated variable is output to CIO 20.
• When CIO 0.00 is turned ON, PID control is executed at the sampling
period intervals according to the parameters set in D200 to D208. The
manipulated variable is output to CIO 20.
• The PID constants used in PID calculations will not be changed if the
proportional band (P), integral constant (Tik), or derivative constant is
changed after CIO 0.00 turns ON.
012C
C: D200 Set value: 300
C+1: D201
0064 Proportional band: 10.0%
C+2: D202 Integral time: 120.0 s
04B0
C+3: D203 Derivative time: 40.0 s
0190
Sampling period: 0.5 s
C+4: D204
0032
C+5: D205
0000
C+6: D206
0494
C+7: D207
0000
C+8: D208
0000
C+9: D209
Work Area
to
C+38: D238
Reverse operation (bit 00: 0), PID constant updating timing = input
condition is ON (bit 01: 0), Manipulated variable output designation:
0% (bit 03: 0),
2-PID parameter = 0.65 (bits 04 to 15: 000 hex)
Manipulated variable output range: 12 bits (bits 00 to 03: 4 hex),
Integral/derivative constants: time designation (bits 04 to 07: 9 hex),
Input range: 12 bits (bits 08 to 11: 4 hex), Manipulated variable limit
control: No (bits 12: 0 hex), PID starting integral manipulated
variable designation = start from same integral manipulated value
as manipulated variable output designation (bit 14: 0 and bit 13: 0)
CS/CJ/NSJ Series Instructions Reference Manual (W474)