Explanation Of Function Code - Eaton PowerXL DA1 Communications Manual

2 Modbus RTU
2.6 Operating mode Modbus RTU

2.6.6 Explanation of function code

2.6.6.1 Function code 03
40
: Reading a holding register
hex
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 DA1 variable frequency drive
with slave address 1.
Master request: 01 03 0005 0001 940B
Rregister address Type name
[hex]
01 Slave address
03 Function code (reading of holding registers)
0005 5
dec
0001 Total number of requested registers
940B CRC
Slave response: 01 03 02 0000 B844
Rregister address Type name
[hex]
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
Modbus RTU for variable frequency drive DA1, DC1, DE1 09/16 MN040018EN www.eaton.com
hex
: The ID is 6, since the motor controller has an offset of +1.
hex