Xylem H-335 - Manual (Page 9)

H-335
H-335 Operation 1-5
GateArcLength =
UserAngle GateRadius
180
Ч Ч π
( ) ( )
[ ]
GateHeight = GateRadius sin SillAngle sin SillAngle - UserAngle −
1.4.3 Arc Length
The ArcLength is distance the gate face moves through the partial curve of a circle. Normally this value is
not recorded by the data logger. The H-335 calculates and reports this value for field test and verification
purposes and is calculated internally in the H-335 using the following equation:
If water is flowing through the gate, the GateHeight cannot be directly measured with a measuring tape
because the water flow sweeps the tape away. However, if the tape is attached to the face of the gate, and is
tangent to the gate, the Arc Length can be directly measured in the field.
1.4.4 Gate Height
The GateHeight is the vertical distance between the bottom of the gate and a horizontal line passing thru
the sill. Normally this value is recorded and used in a weir calculation to determine water flow. The
GateHeight parameter is calculated internally in the H-335 using the following equation:
The GateRadius and SillAngle are constants and must be programmed into the H-335 during installation.
1.5 Programming the Data Recorder
You must prepare your data recorder to receive and record the H-335 data. Since data recorders differ
widely, refer to your recorder manufacturer's directions. In general, program the data recorder to input four
values via the SDI-12 port. Usually only one or two of the parameters is actually recorded. Your data
recorder must issue an “aM!” command, then collect the data with a “aD0 ” command, as explained in
Chapter 2. The H-335 places four data values in its data buffer:
a+AA.AA+BB.BB+CC.CC+DD.DD
Where:
+AA.AA = GateArcLength (inches, meters etc.)
+BB.BB = GateHeight (inches, meters etc.)
+CC.CC = UserAngle (Degrees of angle)
+DD.DD = SensorTemperature ( C)