Campbell Scientific Hydro-Wiper-D Manual from ZebraTech - Manual (Page 6)

Hydro-Wiper operation manual
Zebra-Tech Ltd 5
Operation
Warning
When power to the Hydro-Wiper is switched on, the wiper arm will
immediately start moving.
On power up, if the wiper arm is not at the start position, then the
wiper arm will first rotate to the start position. From the start position,
the brush will wipe across the face of the OBS3+, and then move
back to the start position, thus brushing the OBS3+ face in two
directions.
The Hydro-Wiper will then wait until a control trigger is received from
the data logger before a wipe is performed. The Hydro-Wiper power
consumption between wipes is very low; around 0.05mA.
The Hydro-Wiper regularly monitors the position of the wiper arm
between wipes. If it gets knocked or jolted into the region in front of
the OBS3+, this is detected, and the wiper arm is moved to one side.
When the control line of the wiper control module is driven high (+5
volts) by the data logger, a wipe is initiated. The brush sweeps
across the face of the OBS3+, stops, and then sweeps back in the
opposite direction to the starting position. A wipe typically takes
around 10 seconds to complete.
After the control line has gone high, it will need to go low (0 volt) prior
to going high to initiate another wipe. If the control line stays high,
another wipe will not occur until the control line goes low, then high
again.
The optimal frequency of wiping the OBS3+ depends on the rate of
fouling. Under typical conditions, a wipe interval of 2 to 4 hours
should be adequate to prevent fouling; however this may be
increased or decreased, depending on the characteristics of the site.