Chapter 2 Systems specification
2-34
2-6-2
Scanning
When the CPU operation mode is RUN, the user program executes operations from the start address to the last address. In
addition to executing programs, CPUs perform processing (I/O transfer) for reading and writing I/O status, communication
services, module services, and other services.
The CPU performs these processes repeatedly (cyclically), and one operation is called a scan. The duration of one scan is called
the scan time.
2-6-3
I/O transmission
The SJ Ether series is divided into two methods for reading and writing I/O status: the batch transfer method and the direct I/O
method. The SJ series is divided by the instruction word used.
Input transfer is performed collectively before the program is executed. Therefore, the ON/OFF state of the function memory
(I) does not change during instruction execution. Output transfer is performed collectively after the program is executed.
The CPU is scanned as follows.
･
Process of transferring the ON/OFF status of the mounted input
module to the input function memory (I) at a time
･
Processing when the function memory is forcibly turned ON/OFF by
programmer operation.
･
Process user program from 0 to END command
･
Process of transferring the ON/OFF status of the output function
memory (Q) to the mounting output module
･
Service processing for programmers, self-diagnosis, etc.
NOTE: • Input and output transfers are made only to the modules that are mounted.
・
The scan time is stored in the following special registers with binary values.
R7775: Current scan time (ms)
R7776: Minimum scan time (ms)
R7777: Maximum scan time (ms)
2-6-4
Batch transfer method
Input transfer is performed at the beginning of the scan to ensure that the ON/OFF state (status) of the input function memory (I)
does not change during program execution. Output transfer (contact ON/OFF is common with input (I) on the same scan) is
performed by transferring the output function memory to the output module at the end of the scan. Normal programs use the
collective forwarding instruction word.
入力転送
入出力に対する強制オン／オフ
プログラム実行
出力転送
その他の処理(モニタ、
CPU
動作モード変更 等)
Q100
I05
入力
転送
命令語
LD I05
OUT Q100
プログラム
実行
入力
転送
出力
転送
プログラム
実行
入力端子
I05
機能メモリ
I05
出力端子
Q100
機能メモリ
Q100
Input transmission
Forcible ON/OFF to I/O
Program execution
Output transmission
Other
handling
(Monitor,
CPU
operation mode switching etc…)
Command word
Input
Trans
mission
Program
execution
Out
Trans
missi
on
In
Trans
missi
on
Program
execution
Input terminal I05
Function memory I05
Function memory
Function memory Q100
Output terminal Q100
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 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...
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Page 310: ...Chapter 7 Maintenance...
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