Omron CJ2 CPU UNIT SOFTWARE User Manual page 416

10 CPU Unit Functions
Overall Flow of Synchronous Unit Operation
Synchronous unit operation is performed using the following flow.
1
The Synchronous Units synchronize internal processing with each other and send synchronous
input data to the CPU Unit once each synchronous operation cycle.
2
The CPU Unit stores the synchronous data in memory and executes an interrupt task for syn-
chronous unit operation. This interrupt task is called the synchronous interrupt task.
3
The CPU Unit sends the results of the synchronous interrupt task to all of the Synchronous Units
as synchronous output data.
Normal cyclic
processing
Power turned ON to PLC
1. Synchronous input data refresh
CPU Unit
Synchronous signal
Synchronous Unit A
Synchronous signal
Synchronous Unit B
Item
Synchronous data
refresh
Synchronous
input data refresh
Synchronous out-
put data refresh
Synchronous operation
cycle
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CJ2 CPU Unit
2. Synchronous interrupt task
Interrupted
Write a program for synchronous unit operation, such as for digital cam control.
2. Synchronous interrupt task
Synchronous
operation cycle
Interrupt
task
Internal processing
Internal processing
Synchronous data is refreshed between the CPU Unit and Synchronous Units on the
synchronous operation cycle, which is not affected by the normal cycle time of the
CPU Unit. A special area called the Synchronous Data Refresh Area is allocated for
synchronous data refreshing. The data in this area is exchanged between the Units as
synchronous data.
The input data for the synchronous data refresh is sent from the Synchronous Units to
the CPU Unit.
The output data for the synchronous data refresh is sent from the CPU Unit to the Syn-
chronous Units.
The synchronous operation cycle is used to generate the synchronous signal, which is
used to synchronize the timing of internal processing in the Synchronous Units. This
cycle is also used to refresh synchronous data.
Synchronous Units
1. Synchronous input data refresh
3. Synchronous output data refresh
3. Synchronous output data refresh
Synchronous
operation cycle
Interrupt
task
Internal processing
Internal processing
Internal processing
Internal processing
Description
CJ2 CPU Unit Software User's Manual
Synchronous
operation cycle
Interrupt
task
Time