10 PID CONTROL INSTRUCTIONS
10.1 Overview
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10
I/O data
I/O data consists of input data, such as the set value (SV) and process value (PV), which are set to perform PID operation,
and output data, such as operation results. The I/O data can be set to a word device area with any numbers. Note that all the
data for the number of loops used must be set in the area with consecutive device numbers.
For data assignment, refer to the following.
• Inexact differential: Page 1163 S(P).PIDCONT
• Exact differential: Page 1174 PIDCONT(P)
The I/O data area is divided into two areas: data area assigned for each loop and work area used by the system.
*1 When the PID limit is restricted
*2 When the PID limit is not restricted
Item Description Setting range Remarks
Set value SV A target value in PID control 0 to 2000
*1
In the case of *1, if the SV is out of the
valid range, it will be converted as
follows.
• If the value is smaller than 0, 0 is
used.
• If the value is bigger than 2000, 2000
is used.
-32768 to 32767
*2
Process value PV A feedback data from the control target to the A/D
converter module
-50 to 2050
*1
In the case of *1, if the PV is out of the
valid range, it will be converted as
follows.
• If the value is smaller than -50, -50 is
used.
• If the value is bigger than 2050, 2050
is used.
-32768 to 32767
*2
Automatic
manipulated value
MV A manipulated value calculated by PID operation. The
value is output from the D/A converter module to the
control target.
-50 to 2050
*1
-32768 to 32767
*2
Process value after
filtering
PVf A process value calculated by the following operational
expression
PV
fn
= PV
n
+ (PV
fn-1
- PV
n
)
-50 to 2050
*1
-32768 to 32767
*2
Manual manipulated
value
MV
MAN
Data output from the D/A converter module in manual
mode
-50 to 2050
*1
In the case of *1, if the MV
MAN
is out of
the valid range, it will be converted as
follows.
• If the value is smaller than -50, -50 is
used.
• If the value is bigger than 2050, 2050
is used.
-32768 to 32767
*2
Manual/automatic
selection
MAN/
AUTO
Select the type of output data to the D/A converter
module: manual manipulated value or automatic
manipulated value. In manual mode, the automatic
manipulated value remains unchanged.
0: Automatic
manipulated value
1: Manual
manipulated value
An error occurs if the set value is other
than 0 or 1, and PID operation of the
corresponding loop is not executed.
Alarm ALARM Checks whether the variation rate of the automatic
manipulated value (MV) or process value (PV) is within
the valid range or not. Once the value is set, it is held
until the CPU module is reset.
(1) If the PV is out of the limited range, 1 is set to b0.
(2) If the MV is out of the limited range, 1 is set to b1.
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