Chapter 8 Communication
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Chapter 8 Communication
The communication protocol is designed for the industrial application of bus
turbine flow meter, which is version 1.0, which is mainly used for real-time data
acquisition, flow measurement and flow accumulation control, and currently only
supports register readout function.
8.1. Standard basis
GB/T 19582-2008 The standard is based on the industrial automation network
specification targeted by the Modbus protocol.
8.2. Communication mode
The Modbus serial link is built in 485mi A, and the hardware interface adopts
485communication mode. At present, the interface supports up to 32 extension
networks.
The communication mode is RTU mode, the baud rate range 1200
、
2400
、
4800
、
9600bps
。
8.3. RTU transmission mode
The message contains two 4-bit hexadecimal characters in each 8-bit byte,
and the message needs to be transmitted in a continuous character stream.
Format of each byte (10 bits).
(1) 1 start bit.
(2) 8 data bits, first send the least significant bits.
(3) 1 stop bit.
Message frame description.
Address(1) + Function code(1)+ Data (0-252)+ CRC check(1).
Time sequence
The idle interval of at least 3.5character time distinguishes the message frame,
which is tentatively set as a fixed time 100ms to determine the beginning of the
data frame.
