5-12-2
SJ-Ether CPU cascading control
You must make an important distinction when using "cascade control". In practice, only minor loops are in cascade mode. In
normal operation, the major loop must be set to automatic mode. When more than one control cascade is used, the outermost
control (major) must be in automatic mode, and the innermost control must be in cascade mode.
Note :
Technically, both major and minor loops are "cascades" in a rigorous sense in process control terms. When controlling
the control mode, it may be impossible to maintain this convention. Therefore, remember that the minor loop is in
cascade mode and the major loop is in automatic mode.
SJ-Ether enables you to cascade many PID controls together. You can have many groups of cascade control. However, to
properly control cascade control, the major and minor controls must be the same in the range of data (12/15 bits) and sign to be
set.
As a minor loop, you must program a pointer for the remote set point in R+32 of the control parameter table shown below,
which is required when operating in cascade mode. The pointer must be the address of the control output (R+05) of the major
loop. In a minor loop, in cascade mode, its local SP value (R+02) is ignored and reads the control output of the major loop
instead of its SP value.
When you use the PID view of KPP to view the SP value of the minor loop, KPP automatically reads the control output of the
major loop and displays it as the SP value of the minor loop. The normal SP value (R+02) of the minor loop is not changed.
Here, a loop diagram that is equivalent to the loop parameter described above is drawn below.
As previously described, when the minor loop exits from the cascade mode, the major loop is automatically in manual mode.
Note: DirectSOFT4 and DirectSOFT5 are not supported.
Be sure to use KPP Ver1. 5.0.0 or higher.
+
–
R+02
メジャーループ
マイナーカスケードループ
ループ演算
制御出力：
R
＋
05
カスケード
リモート
SP
ローカル
SP
プロセス変数
セットポイント
ループ演算
制御出力
R+02
SP
XXXX
R+03
PV
XXXX
R+32
XXXX
R+02
SP
XXXX
R+03
PV
XXXX
R+05
XXXX
R+05
XXXX
メジャーループ（自動モード）
マイナーループ（カスケードモード）
ループテーブル
ループテーブル
制御出力
制御出力
リモート
SP
ポインタ
Major loop (Automatic mode)
Loop table
Control output
Minor loop (Cascade mode)
Control output
Remote SP pointer
Major loop
Loop
calculation
Loop
calculation
Minor cascade loop
Control
output
Remote SP
Cascade
Cascade
Set point
Local SP
Process variable
Control
output
Loop table
Summary of Contents for Kostac SJ-Ether Series
Page 1: ...English version of the KOSTAC SJ Ether series user s manual SJ ETHER USER M...
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Page 13: ...1...
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Page 113: ...3 24 Note Refer to 6 3 3 Module Assembly for connections and locks between modules...
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Page 156: ...flashing OFF Not sent H W RX Green flashing Receiving H W OFF Not received H W...
Page 161: ...4 8...
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Page 310: ...Chapter 7 Maintenance...
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