Omron CS1G/H-CPUxxH Instructions Manual page 703

Data Control Instructions
Control Item
data
Bit 00 of C+5 PID forward/reverse
designation
Bit 12 of C+6 Manipulated vari-
able output limit
control
Bits 08 to 11 Input range
of C+6
Bits 04 to 07 Integral and deriva-
of C+6 tive unit
Bits 00 to 03 Output range
of C+6
C +7 Manipulated vari-
able output lower
limit
C +8 Manipulated vari-
able output upper
limit
Note
Sampling Period and
Cycle Time
682
Contents
Determines the direction of the
proportional action.
Determines whether or not limit
control will apply to the manipu-
lated variable output.
The number of input data bits.
Determines the unit for express-
ing the integral and derivative
constants.
The number of output data bits.
(The number of output bits is
automatically the same as the
number of input bits.)
The lower limit for when the
manipulated variable output limit
is enabled.
The upper limit for when the
manipulated variable output limit
is enabled.
1. When the unit is designated as 1, the range is from 1 to 8,191 times the
period. When the unit is designated as 9, the range is from 0.1 to 819.1 s.
When 9 is designated, set the integral and derivative times to within a
range of 1 to 8,191 times the sampling period.
2. Setting the 2-PID parameter ( α ) to 000 yields 0.65, the normal value.
3. When the manipulated variable output limit control is enabled (i.e., set to
"1"), set the values as follows:
0000 ≤ MV output lower limit ≤ MV output upper limit ≤ Max. value of output range
The sampling period can be designated in units of 10 ms (0.01 to 99.99 s), but
the actual PID action is determined by a combination of the sampling period
and the time of PID instruction execution (with each cycle). The relationship
between the sampling period and the cycle time is as follows:
• If the sampling period is less than the cycle time, PID control is executed
with each cycle and not with each sampling period.
• If the sampling period is greater than or equal to the cycle time, PID con-
trol is not executed with each cycle, but PID(190) is executed when the
cumulative value of the cycle time (the time between PID instructions) is
greater than or equal to the sampling period. The surplus portion of the
cumulative value (i.e., the cycle time's cumulative value minus the sam-
pling period) is carried forward to the next cumulative value.
For example, suppose that the sampling period is 100 ms and that the cy-
cle time is consistently 60 ms. For the first cycle after the initial execution,
PID(190) will not be executed because 60 ms is less than 100 ms. For the
second cycle, 60 ms + 60 ms is greater than 100 ms, so PID(190) will be
executed. The surplus of 20 ms (i.e., 120 ms – 100 ms = 20 ms) will be
carried forward.
For the third cycle, the surplus 20 ms is added to 60 ms. Because the sum
of 80 ms is less than 100 ms, PID(190) will not be executed. For the fourth
Setting range
0: Reverse action
1: Forward action
0: Disabled (no limit control)
1: Enabled (limit control)
0: 8 bits 5: 13 bits
1: 9 bits 6: 14 bits
2: 10 bits 7: 15 bits
3: 11 bits 8: 16 bits
4: 12 bits
1: Sampling period multiple
9: Time (unit: 100 ms)
0: 8 bits 5: 13 bits
1: 9 bits 6: 14 bits
2: 10 bits 7: 15 bits
3: 11 bits 8: 16 bits
4: 12 bits
0000 to FFFF (binary)
(See note 3.)
0000 to FFFF (binary)
(See note 3.)
Section 3-18
Change with
ON input
condition
Not allowed