7
box of the telephone line.
• The control unit must be installed on the wall in a position that makes it easy to access the
electric cables, telephone cable, system alarm harness as well as to perform maintenance
on the control unit.
• Do not install the control unit and its modules in places with extreme temperatures and
humidity. For example, don’t place the keypads near heat sources such as radiators
or under direct sunlight, which can affect the liquid crystal display. Place the control
unit and its accessories in a dry room and avoid closing the vent slots which can create a
block, even partially, of internal ventilation.
4.1 Installation of the BUS RS485
The connection is performed by means of 2 conductors plus the ground conductor (negative). It is
recommended to use a shielded cable. The ground is the same used to feed the devices.
Take note that the bus can have parallel branches and shunts, according to the following rules:
• the total length of the bus harness (the addition of all branches and their shunts) must not
exceed 1500 m.
• insert two 120 ohm 1/2W termination resistances on the bus, one resistance between the “+”
and “-“ terminals of the control unit and another resistance at the end of the longer pathway.
Minimum cable sections:
Distance from the control unit
“BUS+” e “BUS-” conductor
Common ground conductor
Up to 400 m
0.22 mm
2
0.22 mm
2
Up to 700 m
0.22 mm
2
0.5 mm
2
From 700 m to 1500 m
0.44 mm
2
0.75 mm
2
See the following example:
120 Ohm resistance
between the BUS+ terminal and
BUS-terminal of the last
peripheral unit.
120 Ohm resistance
between the BUS+ terminal
and BUS- of the control unit
