ProSoft MVI69E-MBS - Page 120

Reference MVI69E-MBS ♦ CompactLogix Platform
User Manual Modbus Serial Enhanced Communication Module
Page 120 of 154 ProSoft Technology, Inc.
June 28, 2017
In the above example, the master's Modbus command to transmit inside the
Modbus packet is as follows.
Slave
Address
Function
Code
Address in
Device
Reg Count
Byte Count
Data
DEC
01
16
7100
2
8
85.37 22.86
HEX
01
10
1B BC
00 02
08
BD 71 42 AA E1 48 41 B6
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.