MVI69E-MBS ♦ CompactLogix™ Platform
Reference
Modbus Serial Enhanced Communication Module
User Manual
ProSoft Technology, Inc.
Page 131 of 159
Example #3: Master is issuing Modbus command with FC 3 to transfer Float data from slave.
Float Flag:
Not applicable with Modbus Function Code 3.
Float Start:
Not applicable with Modbus Function Code 3.
DB Addr
- Tells the master where in its data memory to store the data obtained from the
slave.
Reg Count
- Tells the master how many registers to request from the slave.
Swap Code
- same as above.
Func Code
- Tells the master to read the register values from the slave. FC3.
Addr in Dev
- Tells the master where in the slave's database to obtain the data.
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
DEC
01
3
6100
2
HEX
01
03
17 D4
00 02
In the above example the (Enron/Daniel supporting) slave's Modbus command to
transmit inside the Modbus packet is as follows.
Slave Address Function Code Byte Count
Data
DEC
01
3
8
32.75 275.69
HEX
01
03
08
00 00 42 03 D8 52 43 89
In the above example the (a NON-Enron/Daniel supporting) slave's Modbus command
that is transmitted inside the Modbus packet is as follows.
Slave Address Function Code Byte Count
Data
DEC
01
3
4
32.75
HEX
01
03
04
00 00 42 03
