User manual

Chapter Two Installation
man_905-105_2.9 Page 11
Chapter Two INSTALLATION
2.1 General
The 905U/105S module is housed in a rugged aluminium case, suitable for DIN-rail mounting.
Terminals are suitable for cables up to 2.5 sqmm in size.
All connections to the module should be SELV only. Normal 110/220/240V mains supply should
not be connected to any input terminal of the module. Refer to Section 2.3 Power Supply.
Before installing a new system, it is preferable to bench test the complete system. Configuration
problems are easier to recognise when the system units are adjacent. Following installation, the most
common problem is poor communications on the radio channel or the serial channel. For radio
modules, problems are caused by incorrectly installed antennas, or radio interference on the same
channel, or the radio path being inadequate. If the radio path is a problem (i.e. path too long, or
obstructions in the way), then higher performance antennas or a higher mounting point for the antenna
may fix the problem. Alternately, use an intermediate module as a repeater.
For serial modules, poorly installed serial cable, or interference on the serial cable is a common
problem.
The foldout sheet Installation Guide provides an installation drawing appropriate to most applications.
Further information is detailed below.
Each module should be effectively earthed via a "GND" terminal on the module - this is to ensure that
the surge protection circuits inside the module are effective.
2.2 Antenna Installation
(905U units only)
The 905U module will operate reliably over large distances. The distance which may be reliably
achieved will vary with each application - depending on the type and location of antennas, the degree of
radio interference, and obstructions (such as hills or trees) to the radio path. Typical reliable distances
are :
USA/Canada 15 miles 6dB net gain antenna configuration permitted (4W ERP)
Australia/NZ 12 km unity gain antenna configuration (1W ERP)
Longer distances can be achieved if one antenna is mounted on top of a hill.
To achieve the maximum transmission distance, the antennas should be raised above intermediate
obstructions so the radio path is true “line of sight”. Because of the curvature of the earth, the antennas
will need to be elevated at least 15 feet (5 metres) above ground for paths greater than 3 miles (5 km).
The modules will operate reliably with some obstruction of the radio path, although the reliable
distance will be reduced. Obstructions which are close to either antenna will have more of a blocking
affect than obstructions in the middle of the radio path. For example, a group of trees around the