EXPERT Standard Series User Manual
214
Protocol function
The most important function of Modbus is to read and write parameters, and
different function codes decide different operation requests. Drive Modbus protocol
supports the following function code operations:
Function Code
Function Code Significance
0x03
Read drive function code parameters and run state parameters.
0x06
Modify single drive function code or control parameter, and do
not save after power off.
0x08
Wire diagnosis
0x10
Modify multiple drive function codes or control parameters, and
do not save after power off.
0x41
Modify single drive function code or control parameter, and do
not save after power off.
0x42
Function code management
Drive’s function code parameters, control parameters and state parameters are all
mapped to Modbus read/write register. Read/Write characteristics and range of
function code parameters all comply with instructions in the drive’s user manual. Drive
function code’s group number is mapped to high byte address of the register, while
group index is mapped to low byte address of the register. Drive’s control parameters
are virtualized to drive function code group 50, while drive’s state parameters are
virtualized to drive function code group 51.The correspondence between function
code group number and its mapped register address high byte is as follows:
Group F0: 0x00; group F1: 0x01; group F2: 0x02; group F3: 0x03; group F4: 0x04;
group F5: 0x05; group F6: 0x06; group F7: 0x07; group F8: 0x08; group F9: 0x09;
group FA: 0x0A; group Fb: 0x0B; group FC: 0x0C; group Fd: 0x0D; group FE: 0x0E;
drive control parameter group: 0x32; drive state parameter group: 0x33.
For example, register address of drive function code parameter F3.02 is F3.02,
and register address of drive function code parameter FE.01 is 0xE01.
The overall data frame’s format has been introduced in the above, format and
significance of Modbus protocol’s function code and data part will be introduced in the
following, which is the content of “function code” and “data” parts in the above
mentioned data frame format. These two parts form the application protocol data unit