User manual

905U Wireless I/O Module User Manual
105S Serial I/O Module
Page 62 © October 2001
The following design points should be noted :-
• A test of the radio path between the pump station and the tank station indicated that the radio path
would be reliable provided antennas were installed at 6 m above the ground. At each site, the
coaxial cable would be approx 30 feet in length, so it was decided to use 6 element Yagi antennas
with RG58 coaxial cable - the Yagi antennas would compensate for the loss in the cable.
• At the tank station, there was an existing light pole with a mains power supply - the light pole was
10m high. Permission was obtained to mount the antenna from the pole and to use the power supply
for the radio telemetry module.
As there was no existing electrical panel at this station, a small steel enclosure was installed on the
light pole. A 2 Amp-Hour sealed battery was installed to provide power during any mains failure.
The flow and level transducer were powered from the 24VDC loop supply provided by the module.
• At the pump station, the antenna was mounted on a 10’ J-bracket installed on the roof of the pump
station building. The final height of the antenna was approx 20 feet. Care was taken to align the
Yagi antennas so they pointed at each other. The Yagi antennas were installed with horizontal
polarity - that is, with the elements horizontal. These antennas will not "hear" other radio users on
the same radio channel which generally use vertical polarity.
There was an existing electrical enclosure at the pump station, and the 905U module was installed
inside this enclosure. The module was powered from a 24VDC supply with a 2 Amp Hour sealed
battery as backup.
• At the control station, the 105S module was installed inside the existing control panel enclosure.
The module was powered from an existing 24VDC power supply.