Xylem H-335 - Manual (Page 12)

1-8 Introduction H-335
1.9 Installing the H-335 and setting the mechanical sensor offset
The tilt sensor in the H-335 has a physical ±40 calibrated range. This allows sufficient dynamic range to
measure a gate which opens up to 80 . To work properly, the sensor must be mechanically adjusted during
installation to preserve the available physical dynamic range. This is done by loosening two screws and
rotating the internal sensor assembly. The mechanical offset adjustments are made while monitoring the
SensorAngle parameter. This is the raw sensor reading with no adjustment for slope or offset. The
UserAngle parameter is processed with a slope and offset term to produce the more useful 0.0 to +80.0
reading for the data recorder.
With the gate closed the mechanical offset must be set near (but not beyond) one end of the sensor’s
measurement range. The proper setting depends on which gate arm the H-335 is installed and which side of
the I-beam the H-335 is mounted (see Figure 2). For example; with a gate which can open up to 70 and
which the inclinometer rotates clockwise (while facing the H-335 cover) as the gate opens, the sensor
should be rotated until SensorAngle reads ~ -35 . When this gate is fully open the raw SensorAngle will
read +35 . With the same gate but with the inclinometer installed such that it rotates counter-clockwise
(while facing the H-335 cover) as the gate opens, the sensor must be mechanically adjusted to +35 . When
this gate is fully open the raw SensorAngle will read -35 .
The H-335 fiberglass enclosure can be installed in any
position in the plane of rotation. If possible, locate the
connector on the bottom to prevent water from standing
on the connector. The internal ceramic sensor element
is symmetrical and will still make measurements if
installed upside down. However, if the sensor is upside
down, the calibration will be invalid, the slope will be
wrong and the output data confusing. Check to make
certain the wires exit the red plastic cover at the 2:00
o’clock position when the gate is in the center of its
travel arc.