Details On Synchronous Unit Operation - Omron CJ2 CPU - REV 10-2010 User Manual

10 CPU Unit Functions
Additional Information
Normal I/O refreshing is also performed between the CPU Unit and Synchronous Units. The dif-
ferences between the normal I/O refresh and the synchronous data refresh as listed in the fol-
lowing table.
Data exchange timing
Data exchange cycle
Start of internal process-
ing in Synchronous Units

10-8-2 Details on Synchronous Unit Operation

The time sequence for synchronous unit operation is shown in the following diagram.
Power turned ON to PLC
CPU Unit
(1) Synchronous signal
Synchronous
Unit
Start of internal
processing
Synchronous
Unit
Start of internal
processing
10-84
Item Synchronous data refresh
• Each synchronous operation
cycle. (The normal cycle of the
CPU Unit is interrupted to perform
synchronous data refreshing.)
• Data exchange is synchronized
with the internal processing in the
Synchronous Units.
Constant (always the specified syn-
chronous operation cycle).
Synchronized.
(6) Synchronous output data refresh
(5) Synchronous operation cycle
(4) Synchronous
processing time
(2) Synchronous input
data refresh
• Each normal cycle of the CPU Unit
(after user program execution).
• The timing of the normal I/O refresh
is not related to the timing of inter-
nal processing in the Synchronous
Units.
Inconsistent (or minimum cycle time if
the minimum cycle time is set and the
cycle does not exceed the set time).
Not synchronized.
(5) Synchronous operation cycle
(4) Synchronous
processing time
(2)
(1)
CJ2 CPU Unit Software User's Manual
Normal I/O refresh
(6)
(1)
Time