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3.5 GENERAL INFORMATION ABOUT CONNECTING
DEVICES TO THE BUS
3.6 WIRING THE INPUTS
3.5.1 Bus line termination
As a general precaution, note that the 485 bus cable could cause
disturbances on cables carrying video or comparable signals, if the two
are laid adjacent to each other. We therefore recommend that you use
separate channels for these two types of cable and that you connect
the alarm system bus only with shielded and twisted pair cable with
known impedance of 120 Ohm.
Non-compliance with the above may cause communication errors
or poor quality communication between modules and control panel.
There is also a risk that the conductors of the cables themselves might
not be shielded correctly.
For correct sizing of cables, refer to the table"5.7 Shielded cable
conductor resistance table".
The inputs routed to the control panel or to the peripherals on the bus,
including bidirectional inputs when used as inputs, are of universal
type.
This means that, depending on their physical connection and
their parameter settings on the control panel, they can assume the
configurations shown below.
NC:
detects the opening of a normally closed contact connected
between an input terminal and the respective negative (-V). It is
not capable of detecting a line sabotage state: in the event of
cutting, it can generate an error or alarm; in the event of a line
short-circuit, it does nothing.
NO:
detects the closure of a normally open contact connected
between an input terminal and the respective negative (-V). It is
not capable of detecting a line sabotage state: in the event of a
line short-circuit, it can generate an error or alarm; in the event
of cutting, it does nothing.
Detects the opening of a normally closed contact disposed in
series with a balanced line (on 1.8K) connected between an
input terminal and the respective negative (-V). Detects a
sabotage state due to a line short-circuit. In the event of cutting,
it can generate an error or alarm.
Detects the opening of a normally closed contact disposed in
series with a balanced line (on 1.8K) connected between an
input terminal and the respective negative (-V). Adding a
second balancing resistor (also 1.8K) makes it possible to
distinguish an alarm state from a line sabotage state, both in
the event of cutting and short-circuit.
IMPORTANT
: input balancing resistors, if used, must be installed in
the sensor to which they are associated.
3.6.1 Normally closed (NC)
3.6.2 Normally open (NO)
3.6.3 Single balance
3.6.4 Double balance
The two end devices (the two devices furthest from each other
in an ideal layout) must balance the line with the appropriate
end-of-line resistor (120 ohm). On some devices, this resistor
is installed on-board and can be activated by means of a
jumper or DIP switch. 2 end-of-line resistors are supplied with
the control panel, for use when a device without an on-board
termination (e.g. RFID key reader) is connected to the end of
the line.
IMPORTANT
: the control panel can be positioned at any point
along the line, provided that the line is correctly terminated in
a 120 Ohm balancing resistor at both ends, as shown in the
guideline diagram.
It is recommended to use a shielded cable for the
connections,with one end of the shield connected to V-
and the other left free.
It is recommended to use a shielded cable for the
connections,with one end of the shield connected to V-
and the other left free.
In order to guarantee compliance with standard EN 50131-
1, all the alarm, anomaly and control zones must be at
least in double balance. Single balance may be enough for
sabotage.
IMPORTANT
: for correct communication between the devices
connected to the bus, it is good practice for the devices themselves to
be interconnected without branches, i.e. avoid star connections as far
as possible. If the use of branches is unavoidable, make sure that they
are as short as possible. Consequently, it is advisable to route the bus
cable correctly by adhering to the ideal connection and minimising any
deviation from it. The best way to connect the devices is to use the “in
and out” method.
CONNECTION TO THE BUS TERMINALS
EXAMPLE OF "IN AND OUT" TYPE CONNECTION
FROM THE
CONTROL PANEL
TO THE
NEXT MODULE
MODULE 1
-V +V A B
CONNECTION TO THE BUS TERMINALS: GUIDELINE DIAGRAM
MODULE 1
-V +V TO B
-V +V
BUS
A B
MODULE N-1
-V +V A B
MODULE N:
ENABLE BUS
BALANCING
BUS
CONTROL PANEL:
ENABLE BUS
BALANCING
BUS
-V +V A B
MODULE 2
-V +V TO B
IN
-V
NC
ALARM
IN
-V
NO
ALARM
IN
-V
NC
1K8
ALARM
IN
-V
NC
NC
TAMPER
ALARM
