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Appendix II RS485 Communication protocol
II-1 Communication protocol
II-1-1 Communication content
This serial communication protocol defines the transmission information and
use format in the series communication Including: master polling( or broadcast)
format; master encoding method, and contents including: function code of action,
transferring data and error checking. The response of slave also adopts the same
structure, and contents including: action confirmation, returning the data and error
checking etc. If slave takes place the error while it is receiving information or cannot
finish the action demanded by master, it will send one fault signal to master as a
response.
Application Method
The inverter will be connected into a “Single-master Multi-slave” PC/PLC
control network with RS485 bus.
Bus structure
(1) Interface mode
RS485 hardware interface
(2) Transmission mode
Asynchronous series and half-duplex transmission mode. For master and slave,
only one of them can send the data and the other only receives the data at the same
time. In the series asynchronous communication, the data is sent out frame by frame
in the form of message
(3) Topological structure
Single-master and multi-slave system. The setting range of slave address is 0 to
247, and 0 refers to broadcast communication address. The address of slave for
network must be exclusive.
II-1-2 Communications connection
Installation of RS485 communication module:
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