Omron CJ - 08-2008 - Data Exchange with CPU Bus Units; Special I;O Units

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Data Exchange with CPU Bus Units Section 8-6
8-6 Data Exchange with CPU Bus Units
This section describes how data can be exchanged between Special I/O Units
or CJ-series CPU Bus Units, and the CPU Unit.
8-6-1 Special I/O Units
Special I/O Unit Area
(I/O Refreshing)
Data is exchanged each cycle during I/O refreshing of the Special I/O Unit
Area. Basically, 10 words are allocated to each Special I/O Unit based on its
unit number setting. Refer to the operation manuals for individual Special I/O
Units for details.
The Special I/O Unit Area ranges from CIO 2000 to CIO 2959 (10 words
× 96
Units).
Transfer of Words Allocated in DM Area
There are three times that data may be transferred through the words allo-
cated to each Unit. The timing of data transfers depends on the model being
used.
1,2,3... 1. Data transferred when the PLC is turned on.
2. Data transferred when the Unit is restarted.
3. Data transferred when necessary.
Some models transfer data in both directions, from the DM Area to the Unit
and from the Unit to the DM Area. See the Unit’s Operation Manual for details
on data transfers.
Special I/O Unit Words in the DM Area: D20000 to D29599 (100 Words x 96 Units)
Each Special I/O Unit is allocated 100 words in the DM Area in the range of
D20000 to D29599 (100 words
× 96 Units). These 100 words are generally
used to hold initial settings for the Special I/O Unit. When the contents of this
area are changed from the program to reflect a change in the system, the
Restart Bits for affected Units must be turned ON to restart the Units.
Special I/O Unit Area
10 words/Unit
CPU Unit
Special I/O Unit
Transferred in
I/O refreshing
Transferred
when power is
turned on or
the Unit is
restarted.
CPU Unit
Special I/O Unit
DM Area for Special I/O
Units 100 words/Unit
Transferred
each cycle and
when
necessary.