Appendix B __________________________________________________________ SDI-12 Protocol
VAISALA______________________________________________________________________ 195
APPENDIX B
SDI-12 PROTOCOL
SDI-12 is a standard for interfacing data recorders with microprocessor-
based sensors. The name stands for serial/digital interface at 1200 baud.
More information of the complete SDI-12 standard text is available
from the SDI-12 website:
.
SDI-12 Electrical Interface
The SDI-12 electrical interface uses the SDI-12 bus to transmit serial
data between SDI-12 data recorders and sensors. The SDI-12 bus is the
cable that connects multiple SDI-12 devices. This is a cable with three
conductors:
-
Serial data line
-
Ground line
-
12 V line.
The SDI-12 bus can have at least 10 sensors connected to it. The bus
topology is a parallel connection, where each of the three wires of
different sensors are connected in parallel.
