Users’ Manual
ESM-40S High sensitivity settlement monitoring system
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5 SENSOR WIRING
A T-type connector (with female connector port for connecting to sensor) along with two separate male
female connector are provided for the signal cable connection.
5.1 For sensors with SDI-12 output option
The settlement sensor with SDI-12 interface output requires 3 core bus cable. SDI-12 is an acronym for
"Serial Data Interface at 1200 Baud". It is an asynchronous ASCII, serial communications protocol.
Instruments with SDI-12 interface are typically low power (12 V); often used in remote locations, and
usually, communicate with a datalogger or RF Nodes and Gateways. In this master-slave configuration,
the datalogger typically acts as the master (SDI-12 Recorder and Interrogator) to data monitoring
instruments, which are the slaves (SDI-12 sensors). One master can communicate with multiple slaves; so
the SDI-12 protocol requires that each device in the serial network be identified with a unique address,
which is represented by a single ASCII character.
This communication is achieved by digital communication along a single serial line. The digital addressing
system allows an SDI-recorder to send out an address over a single line that is connected to sensors. Only
the pre-configured sensor matching that address will respond (handshake). The other sensors on the same
line will not respond until called and typically stay in "sleep mode" (low power mode), until called (often in
a sequence) at a later time by the SDI-Recorder (Master). The sensor with SDI-12 interface bears a
manufacturing serial number and an identity or address can be assigned to it during the installation process.
The identities are 0-9, a-z & A-Z.
The connection details of 3 core SDI-12 bus cable to male and female connectors is shown in figure below.
5-pin male connector
Wiring diagram
5
2
4
1
3
Green: SIG
Black: GND
Red: +12V
5-pin female connector
Wiring diagram
5
2
4
1
3
Green: SIG
Black: GND
Red: +12V
Figure 5-1 T type connector with male & female connectors for connecting sensor bus
cable
Connects to male connector
of the sensor
Female connector
Cable gland
Male connector
Cable gland
