Ex: Bacnet - Modbus (Analog Objects-Registers) - ICC XLTR-1000 Instruction Manual

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11.4 Ex: BACnet - Modbus (Analog Objects-Registers)

This example exhibits two networks that both use an object value scheme to
exchange data. In this scenario, the database endianness is irrelevant if the data
types are the same for both networks. This example shows communication
between a BACnet network and a Modbus network using two 16-bit analog value
BACnet objects and two 16-bit Modbus holding registers. As shown in Figure 29,
the values from the BACnet network are stored into the database with big-endian
byte ordering. Figure 30 shows the values from the BACnet network being stored
into the database with little-endian byte ordering. Regardless of the byte-ordering
scheme used, the two holding registers on the Modbus network receive the same
values. Notice that in both cases, analog values 1 and 2 have values of 0x1234
and 0x5678, respectively, while holding registers 1 and 2 also have values of
0x1234 and 0x5678, respectively. The only difference between the two cases is
how the data is being stored internally on the gateway itself.
Figure 29: BACnet - Modbus (Analog Objects & Registers) Big Endian
Figure 30: BACnet - Modbus (Analog Objects & Registers) Little Endian
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