VFD can set different delay time for response according to different application.For RTU mode,the actual delay time
for response is 3.5 characters interval at least.For ASCII mode,the actual delay time for response is 1 ms at least.
5. Protocol Function
The main functions of Modbus are read and write parameters.Different function codes need different operation
request.The modbus protocol of VFD support the operations in the following table.
Read parameters of VFD,including function code parameters,control parameters and status
parameters.
Rewrite single function code or control parameter with 16bit length,the value of the
parameter can’t be saved after VFD power off.
Rewrite multiple function code or control parameters,the vaule of the parameters can’t be
saved after VFD power off.
Rewrite single function code or control parameter with 16bit length,the value
can be saved after VFD power off.
Manage function code of VFD.
Rewrite multiple function code or control parameters,the vaule of the parameters can be
saved after VFD power off.
All the function code, control parameters and status parametes of VFD are mapping to the read/write register of
Modbus.The group number of function code is mapping to the high byte of register address and the index address in
the group is mapping to the low byte of register address.The corresponding relationship between group number and
register address is shown in following table.
High bye of mapping
address
High bye of mapping
address
For example, the register address of function code A3.02 is 0x0302, and the register address of the first control
parameter (Control command 1) is 0x3200.