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Device
Data item
(s)+9
PV change rate
limit (PVL)
(s)+10
(Fixed value)
(s)+11
Derivative gain
(K
)
D
(s)+12
(Fixed value)
(s)+13
(Fixed value)
*1 For the PID operational expression set in the operational expression selection, refer to the following.
MELSEC-Q/L/QnA Programming Manual (PID Control Instructions)
Precautions
The following table shows the CPU modules applicable to the PID control instructions (inexact differential) and the PID control
instructions (exact differential).
CPU module model
Basic model QCPU
The first five digits of the serial number are '04121' or lower.
The first five digits of the serial number are '04122' or higher
High Performance model
The first five digits of the serial number are '05031' or lower.
QCPU
The first five digits of the serial number are '05032' or higher.
Redundant CPU
Universal model QCPU
LCPU
: Applicable, : Not applicable
Description
Setting range
With PID limits
Set the variation limit
0 to 2000
between the previous PV and
the present PV.
When the PV variation is
greater than the limit value,
bit 0 (b0) of the alarm device
is set to '1'.
PV variation is not limited.
(Even if the PV variation
exceeds the limit value, the
actual PV variation is used as
it is for performing the PID
operation.)
0
Set a duration (delay in
0 to 32767
action) for derivative action.
(unit: 0.01)
As the setting value
increases, the duration
If setting value >
becomes smaller and action
30000
becomes closer to exact
K
= Infinite ()
D
differential.
Ideal value K
= 8.00
D
0
0
Setting
side
Without PID
limits
-32768 to 32767
User
0
User
0 to 32767
User
(unit: 0.01)
If setting value >
30000
K
= Infinite ()
D
0
User
0
User
Inexact differential
6 PID CONTROL INSTRUCTION
6.1 PID Control Instruction (Inexact Differential)
Processing when the
setting data are outside
the setting range
In the case of "With PID
limits", the PID operation is
performed after values are
replaced as follows:
• If the PVL value is less
than 0, the value is clipped
to 0.
• If the PVL value is greater
than 2000, the value is
clipped to 2000.
An error occurs and the PID
operation for the
corresponding loop is not
performed.
Exact differential
239
6
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