!
7-18
Section
Data Control Instructions
427
Description
PID(––) performs PID control based on the parameters specified in P1 through
P1+6.
When the execution condition OFF, PID(––) is not executed. When the execu-
tion condition is ON, PID(––) carries out PID control according to the designated
parameters. It takes the specified input range of binary data from the contents of
IW and carries out the PID action according to the parameters that are set. The
result is then stored as the manipulated variable in OW.
The following table shows the function of the parameter words.
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 number
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 (Tik)/
sampling period (
τ
)
Sets the strength of integral action. Increasing this value strengthens the
integral action. It must be BCD from 0001 to 8191, or 9999. A setting of
9999 disables integral control.
Set the integral time divided by the sampling time.
P1+3
00 to 15
Derivative time
(Tdk)/sampling peri-
od (
τ
)
Sets the strength of derivative action. Increasing this value strengthens the
derivative action. It must be BCD from 0001 to 8191, or 0000.
(A setting of 0000 disables derivative control.)
Set the derivative time divided by the sampling time.
P1+4
00 to 15
Sampling period (
τ
)
Sets the interval between samplings of the input data. It must be BCD from
0001 to 1023. The period will be from 0.1 to 102.3 s
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
(
α
)
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 03
Output range
Determines the number of bits of output data. This setting must be be-
tween 0 and 8, 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.)
Caution
Changes made to the parameters will not be effective until the execution condi-
tion for PID(––) goes from OFF to ON.
Note
Do not use PID(––) in the following situations; it may not be executed properly.
In interrupt programs
In subroutine programs
In interlocked program sections (between IL and ILC)
In jump program sections (between JMP and JME)
In step ladder program section (created with STEP)
When the execution condition is ON, PID(––) performs the PID calculation on
the input data when the sampling period has elapsed. The sampling period is the
time that must pass before input data is read for processing.
