ST160/161 Installation Video
The ST160/161 is for stand alone soil moisture sensors or soil moisture sensors combined with valve control.
SN120 User Manual
The SN120 is for use with an Altrac Wind Machine Station. Installation instructions for soil moisture probe are in a pdf below.
You must have a 12V battery installed on your wind machine in order for the soil moisture probe to function.
Soil Moisture Hub Extension Wiring