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3 Memory Allocations
CJ-series EtherCAT Slave Units Operation Manual (W541)
3-3 DM Area Allocations
3
3-3-1 Overview of the Allocated DM Area Words
3-3 DM Area Allocations
This section describes DM area allocations for the EtherCAT Slave Unit.
The various kinds of data are stored in the offset positions shown in the following diagram, from the
beginning word in the area for each Unit.
The beginning word m is calculated by the following equation:
Beginning word m = D30000 + (100 x unit number)
Precautions for Correct Use
Setting results are refreshed when the Unit restarts or when the Unit is powered ON.
This section provides the details of the allocated DM area words.
Set values in this area to specify the input and output words used by the EtherCAT Slave Unit. Changes
to the I/O Communication Area Setting Table require a Unit restart to take effect.
Relationship Between I/O Communication Area and Process Data Objects
IN and OUT data area settings determine where the PDO data that is exchanged over the EtherCAT
network is allocated in the memory of the CPU Unit.
The IN data area is used to send (TxPDO) data to the EtherCAT master.
The OUT data area is used to receive (RxPDO) data from the EtherCAT master.
3-3-1 Overview of the Allocated DM Area Words
3-3-2 Details of the Allocated DM Area Words
I/O Communication Area Setting Table
Offset
Bit
Data direction
I/O Communication Area Setting Table
(7 ch)
(Not used)
EtherCAT Slave Unit to CPU Unit
15
8
7
0
m
m+6
m+13
m+99
I/O Communication Area Reference Table
(6 ch)
CPU Unit to EtherCAT Slave Unit
m+12
m+7
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