405
Special Instructions Section 5-28
5-28-15 PID CONTROL – PID(––)
Limitations DM 6144 to DM 6655 cannot be used for IW, P1 to P1+32, or OW.
P1 to P1+32 must be in the same data area.
!Caution A total of 33 continuous words starting with P1 must be provided for PID(––)
to operate correctly. Also, PID(––) may not operate dependably in any of the
following situations: In interrupt programs, in subroutines, between IL(02) and
ILC(03), between JMP(04) and JME(05), and in step programming
(STEP(08)/SNXT(09)). Do not program PID(––) in these situations.
Description PID(––) performs PID control based on the parameters specified in P1
through P1+6. The data in IW is used to calculate the output data that is writ-
ten to OW. The following table shows the function of the parameter words.
When the execution condition is OFF, PID(––) is not executed and the instruc-
tion’s data is maintained. While the execution condition is OFF, the desired
output data can be written directly to OW for manual control.
IW: Input data word
IR, SR, AR, DM, EM, HR, LR
Ladder Symbol Operand Data Areas
OW: Output data word
IR, SR, AR, DM, EM, HR, LR
P1: First parameter word
IR, SR, DM, EM, HR, LR
PID(−− )
IW
P1
OW
Word Bits Parameter name Function/Setting range
P1 00 to 15 Set value (SV). This is the target value for PID control. It can be set to any binary num-
ber with the number of bits set by the input range parameter.
P1+1 00 to 15 Proportional band width. This parameter specifies the proportional band width/input range ratio
from 0.1% to 999.9%. It must be BCD from 0001 to 9999.
P1+2 00 to 15 Integral time Sets the integral time/sampling period ratio used in integral control. It
must be BCD from 0001 to 8191, or 9999. (9999 disables integral con-
trol.)
P1+3 00 to 15 Derivative time Sets the derivative time/sampling period ratio used in derivative control.
It must be BCD from 0001 to 8191, or 0000.
P1+4 00 to 15 Sampling period Sets the interval between samplings of the input data from 0.1 to
102.3 s. It must be BCD from 0001 to 1023.
P1+5 00 to 03 Operation specifier Sets reverse or normal operation. Set to 0 to specify reverse operation
or 1 to specify normal operation.
04 to 15 Input filter coefficient Determines the strength of the input filter. The lower the coefficient, the
weaker the filter.
This setting must be BCD from 100 to 199, or 000. A setting of 000 sets
the default value (0.65) and a setting of 100 to 199 sets the coefficient
from 0.00 to 0.99.
P1+6 00 to 07 Output range Determines the number of bits of output data. This setting must be
between 00 and 08, which sets the output range between 8 and 16 bits.
08 to 15 Input range Determines the number of bits of input data. This setting must be
between 00 and 08, which sets the input range between 8 and 16 bits.
P1+7 to
P1+32
00 to 15 Work area Do not use.
(Used by the system.)
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