MD280/MD280N User Manual                              Appendix             
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Appendix Communication Protocol 
    MD280 series of inverter provides RS485 communication interface, User 
can carry out centralized monitoring through PC/PLC to get operating 
requirements. ˄ Set the inverter running command, function code 
parameters and read the work status and fault information,etc˅ The 
RS232/RS485 conversion device is required if the interface of the external 
device is RS232. 
 
1
About Protocol 
This serial communication protocol defines the transmission information 
and use format in the series communication and it includes master-polling 
(or broadcasting) format, master coding method and the content includes 
function code of action, transferring data and error checking. The response 
of slave is the same structure, and it includes action confirmation, returning 
the data and error checking etc. If slave takes place the error while it is 
receiving the information or cannot finish the action demanded by master, it 
will send one fault signal to master as a response. 
 
2
Application Method 
The inverter will be connected into a “Single-master Multi-slave” PC/PLC 
control net with RS232/RS485 bus. 
 
3
Bus structure 
1˅Interface mode 
RS485 Hardware interface. The RS232/RS485 conversion device is 
required when the interface of the external device is RS232. 
 
2˅Transmission mode 
There provide asynchronous series and half-duplex transmission mode. At 
the same time, just one can send the data and the other only receives the 
data between master and slave. In the series asynchronous 
communication, the data is sent out frame by frame in the form of 
message. 
3˅Topological mode 
In Single-master system, the setup range of slave address is 0 to 247. Zero 
refers to broadcast communication address. The address of slave must is 
exclusive in the network. That is one condition of one slave machine. 
4
Protocol Description
 
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