SDI-12 is a communication standard often used with sensors. On the Flexi1, it is often used for Soil Moisture Probes (SMP).


The Flexi 1 exposes 3 screw terminals for SDI-12:

  • VOUT: provides power to the sensor. The voltage supplied will be that of the Flexi1's external power. If the reverse voltage protection jumper is out (enabling reverse voltage protection), the voltage will be 0.7V below the external power to the Flexi1. The current limit is 500mA.
  • DATA: communication to the sensor. 2 way, half duplex SDI-12 communication at 5V. Or less than 5V if external power to the Flexi1 is less than 5V.
  • GND: ground connection to the sensor.


Aquacheck probes use the following wiring colours:

  • Brown = Positive - connect to VOUT
  • Blue = Data - connect to DATA
  • Green/Yellow = Ground - connect to GND