8 Modbus RTU
8.3 Operating mode Modbus RTU
DC1 variable frequency drive 12/13 MN04020003Z-EN www.eaton.com 147
8.3.4 Explanation of function code
8.3.4.1 Function code 03
hex
: Reading of holding registers
This function reads the content of a number of consecutive holding registers
(specified register addresses).
Example
Reading the status and fault word (ID 6) of the DC1 variable frequency drive
with slave address 1.
Master request: 01 03 0005 0001 940B
hex
Slave response: 01 03 02 0000 B844
hex
Register [hex] Name
01 Slave address
03
Function code (reading of holding registers)
0005
5
dez
: The ID is 6, since the master controller has an offset of +1.
0001
Total number of requested registers
940B CRC
Register [hex]
Name
01 Slave address
03 Function code (reading of holding registers)
02 Number of consecutive data bytes (1 register = 2 byte)
0000 Content (2 byte) for register 6: 0
B844 CRC
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