User Guide

User Guide

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5 SDI-12

5.1 Introduction of SDI-12

SDI-12 communication adopts three wires, two of which are sensor power supply wires and the other is

SDI-12 signal wire.

Each sensor on the SDI-12 bus has a unique address, which can be set to ‘0’, ‘1’ ~ ‘9’, ‘A’ ~ ‘Z’, ‘A’ ~ ‘Z’.

The SDI-12 address of the SenseCAP ORCH S4 defaults to ‘0’. The instructions supported by this sensor

are shown in the next chapter, where each instruction conforms to the SDI-12 v1.4.

The sensor is powered by a DC power supply of 3.6~16V. After the sensor is powered on, it will go into

sleep mode immediately and wait for the data acquisition equipment to give instructions. SDI-12 uses baud

rate 9600bps, 1 start bit (high level), 7 data bits (high 0 and low 1, anti-logic), 1 even parity bit and 1 stop

bit.

The sequence of each byte sent is shown in the following figure: