Data Exchange; Special I/O Units - Omron CJ2 - 02-2010 User Manual

8 I/O Allocations and Unit Settings
8-2-2

Data Exchange

This section describes how data can be exchanged between Special I/O Units or CPU Bus Units, and
the CPU Unit.

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 man-
uals 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).
Special I/O Unit Area
10 words/Unit
Transfer of Words Allocated in DM Area
There are three times that data may be transferred through the words allocated to each Unit. The
timing of data transfers depends on the model being used.
• Data transferred when the PLC is turned ON.
• Data transferred when the Unit is restarted.
• 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 × 96 Units)
Data is transferred to these words in the DM Area for initial settings for Special I/O Units. When the
contents of this allocated words are changed from the program to change the system, the Special
I/O Unit Restart Bit (A502.00 to A507.15) must be turned ON to restart the Unit.
DM Area for Special I/O Units
100 words/Unit
8-24
Special I/O Unit
CPU Unit
Transferred in
I/O refreshing
Special I/O Unit
CPU Unit
Transferred
when power is
turned on or the
Unit is restarted.
Transferred
each cycle
and when
necessary.
CJ2 CPU Unit Software User's Manual