Basic Operation
2-2
Data Exchange Model
Internally, the data exchanged on the sub-network, and
the data exchanged on the higher level network, resides
in the same memory.
This means that in order to exchange data with the sub-
network, the higher level network simply reads and
writes data to memory locations specified using the
ABC Config Tool. The very same memory locations
can then be exchanged on the sub-network.
The internal memory buffer is divided into three areas
based on their function:
• Input Data (512 bytes)
This area can be read by the higher level net-
work (in this case Modbus RTU).
• Output Data (512 bytes)
This area can be read/written by the higher lev-
el network (in this case Modbus RTU).
• General Data (Up to 1024 bytes)
This area cannot be accessed from the higher
level network, but may be used for transfers be-
tween individual nodes on the sub-network, or
as a general “scratch pad” for data. The actual
size of this area depends on the amount of data
that is exchanged on the sub-network. The gate-
way can handle up to 1024 bytes of General Data.
Memory Map
When building the sub-network configuration using the ABC Config Tool, the different areas described
above are mapped to the memory locations (addresses) specified below.
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