Manual

101
DXi User Manual
Chapter 12: Troubleshooting
Control Devices
(Rain Sensors, Freeze sensors, Etc.)
Many commercial sensor devices available in today's market take advantage of the
common ground configuration to control watering operations. Devices such as
rain sensors, freeze sensors, moisture sensors, etc. employ a control system which
interrupts the common ground line of watering stations to control the shutdown of
stations.
These devices have inherent limitations:
1. They exhibit "contact bounce" or jitter when the on/off threshold is reached.
This may have adverse affects on pump systems.
2. Since they interrupt common lines, non-irrigation programs such as lighting
programs are also affected.
3. It may be difficult to identify/interrupt the "common" wire if multiple commons
come in from the field.
The DXi avoids these limitations with two dedicated contact closure inputs available
at the MV/Sensor board, Alarm Inputs 1 and 2. Rain or freeze sensors can be
connected that will accomplish the controller shutdowns without breaking the
common ground line.