5. modbus COMMUNICATION PROTOCOL
5.1 General
The communication system by the modbus protocol is that the communication is always started from the master
station and a slave station responds to the received message.
Transmission procedures is as shown below.
1） The master station sends a command message to a slave station.
2） The slave station checks that the station No. in the received message matches with the own station No. or
not.
3） If matched, the slave station executes the command and sends back the response message.
4) If mismatched, the slave station leaves the command message and wait for the next command message.
a) In case when the station No. in the received command message matches with the own slave station No.
Command message
Response message Slave to master
Master to slave Data on
the line
b) In case when the station No. in the received command message mismatches with the own slave station
No.
Command message
(Not respond) Slave to master
Master to slave Data on
the line
The master station can individually communicate with any one of slave stations connected on the same line upon
setting the station No. in the command message.
这是表的通讯你帮我看看要如何处理啊
我用标准的通讯案例读出来的数据是占2个位的，不知咋搞