ProSoft Technology CompactLogix MVI69E-MBS User Manual page 129

MVI69E-MBS ♦ CompactLogix™ Platform
Modbus Serial Enhanced Communication Module
In the above example, the master's Modbus command to transmit inside the Modbus
packet is as follows.
Slave
Address
01
DEC
01
HEX
In this example, the master's Modbus packet contains the data byte and data word
counts that have been doubled from the amount specified by Reg Count due to the Float
flag set to Y. Some slaves look for the byte count in the data packet to know the length
of the data to read from the wire. Other slaves know at which byte the data begins and
read from the wire the remaining bytes in the packet as the data the master is sending.
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Function Address in Reg Count
Code Device
16 7100 2
10 1B BC 00 02
Data
Byte Count
8 85.37
BD 71 42 AA E1 48 41 B6
08
Reference
User Manual
22.86
Page 129 of 159