Campbell Scientific Hydro-Wiper-D Manual from ZebraTech - Manual (Page 5)

Hydro-Wiper operation manual
Zebra-Tech Ltd 4
The wiper control module is not water proof, and should be mounted
inside a weather-proof housing, ideally adjacent to the controlling
data logger.
The ground (GND) connection of the wiper control module must be
connected to both the +12 volt supply ground, and the data logger
control ground.
The power supply to the Hydro-Wiper must be between 8 and 15
volts DC, and capable of supplying around 90mA during a wipe, and
momentarily up to 500mA if the wiper arm becomes jammed.
The control connection of the wiper control module is connected to
the data logger control port. The control port needs driven to +5 volts
for longer than 10 milliseconds to trigger a wipe.
The wiper control module is fitted with plug-in screw terminals. This
simplifies passing the cable through a gland in the data logger
cabinet.