ABB A43

Communication with Modbus
A43/A44 104 2CMC48001M0201
User Manual Revision: C
Response frame
Example of
a response
A response frame has the following structure:
Slave Address
Function Code
Start Address
No. of Registers
Error Check
The following is an example of a response:
Slave address
0x01
Function code
0x10
Register address, high byte
0x8A
Register address, low byte
0x00
No. of registers, high byte
0x00
No. of registers, low byte
0x03
Error check (CRC), high byte
0xAA
Error check (CRC), low byte
0x10
In the example above the slave with the Modbus address 1 responds to a write
request. The first register is 0x8A00 and 0x03 registers have been successfully
written to.
9.2.3 Function Code 6 (Write single register)
General
Request frame
Example of
a request
Function code 6 can be used as an alternative to function code 16 if there is
only one register to be written. It can, for example be used to reset the power
fail counter.
A request frame has the following structure:
Slave Address Function Code Register Address Register Value Error Check
The following is an example of a request (reset power fail counter):
Slave address
0x01
Function code
0x06
Register address, high byte
0x8F
Register address, low byte
0x00
No. of registers, high byte
0x00
No. of registers, low byte
0x01