10.5 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 value 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 value of the parameters can be saved
after VFD power off.
All the function code, control parameters and status parameters 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.
10.6 Control parameters and status parameters of VFD
The control parameters of VFD can achieve the function such as startup,stop,setting operating frequency
and so on.Retrieving the status parameters of VFD can obtain the parameters such as operating
frequency,output current,output torque and so on.
1). Control parameter
The control parameters of VFD are shown in following table.
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