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Appendix | Digital Interface RS485
ACC5703
A 4
Digital Interface RS485
A 4.1
Hardware Interface
The interface is a half-duplex RS485 interface, which means that one cable pair is jointly used for sending and
receiving.
Baud rate
230400 b/s
Data format
1 start bit, 8 data bits, 1 parity bit even, 1 stop bit
Bus address
126
Fig. 16 Settings of the RS485 interface
A terminating resistance of 120 Ω is required between the A- and B-line of the RS485 interface at the begin
-
ning and the end of the RS485 bus. A terminating resistor of the RS485 line is not incorporated in the sensor.
It is therefore allowed to connect several sensors to one bus cable.
A 4.2
Protocol
The sensor acts as RS485 slave. As the system uses a half-duplex protocol, only the master can initiate
communication. Each device at the RS485 bus requires its own address. The master sends an enquiry with
the destination address to the bus and only the slave with this address answers accordingly.