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6193-5201
Chapter Two
INSTALLATION
2.1 General
The RM-240 module is suitable for DIN-rail mounting. Terminals will accept wires up to
2.5 sqmm (12 gauge) in size.
All connections to the module must be SELV. Normal 110-240V mains supply
should not be connected to any terminal of the RM-240 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 recognize when the system units are adjacent.
Following installation, the most common problem is poor communications 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 (ie path too long, or obstructions in
the way), then higher performance antennas or a higher mounting point for the antenna
may rectify the problem. Alternately, use an intermediate RM-240 Module as a repeater.
Each RM-240 module should be effectively earthed via the “GND” terminal on the
RM-240 module – this is to ensure that the surge protection circuits inside the
RM-240 module are effective.
2.2 Antenna Installation
The RM-240 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 buildings or trees)
to the radio path.
The maximum range achievable depends on the regulated RF power permitted in your
country, and whether you use separate transmit and receive antennas. With a single
antenna, 5 km (3 miles) can be achieved in USA, Canada and Australia (4W ERP) and 1km
in Europe (100mW ERP). With separate transmit and receive antennas, more than 10km
(6 miles) can be achieved in USA, Canada and Australia and more than 5 km in Europe.
To achieve the maximum transmission distance, the antennas should be raised above
intermediate obstructions so the radio path is true “line of sight”. The modules will oper-
ate 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 block-
ing affect than obstructions in the middle of the radio path. The RM-240 modules pro-
vide a diagnostic feature which displays the radio signal strength of transmissions (refer
Diagnostics section).
Line-of-sight paths are only necessary to obtain the maximum range. Obstructions will
reduce the range, however may not prevent a reliable path. A larger amount of obstruc-
tion can be tolerated for shorter distances. For short distances, it is possible to mount
the antennas inside buildings. An obstructed path requires testing to determine if the path
will be reliable – refer the section 6 of this manual.