Xylem H-312-22 - Manual (Page 14)

2-6 Installation
H-312
2.7 Wiring and Installation Precautions
The shield in the hook-up cable must be connected to the data logger ground.
The data recorder must be earth grounded.
The H-312 requires that the water be at ground potential. Mother Nature takes care of this
for surface and ground water.
Make certain the seals in the liquid tight cable fittings on the dry air junction box are tight.
Make certain the dry air junction box lid is screwed on and sealed properly.
Make certain the screened vent port on the lid of the dry air junction box is not covered or
blocked.
Make certain the end of the vent tube inside the dry air junction box is not plugged or
blocked.
Check the desiccant packs. Replace if necessary
2.8 Programming Your Data Recorder
You must prepare your data recorder to receive and record the H-312 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 4. The H-312 places four parameters in its data buffer:
a+AA.AAA+BB.BBB+CC.C+DD.D
Where:
a = SDI-12 address 0-9, A-Z
AA.AAA = Stage (feet, inches, meters etc.)
BB.BBB = Pressure (PSI)
CC.C = Temperature (C)
DD.D = Sensor Supply Voltage (Volts)