Cabling Requirement Multidrop Modbus - Crowcon Xgard Bright Bedienungsanleitung

Xgard Bright
due to cable resistance. For example, a nominal dc supply at the control panel of 24V
has a guaranteed minimum supply of 18V. The maximum voltage drop is therefore 8V.
Xgard Bright can demand up to 95mA and so the maximum loop resistance allowed
is approx 80Ω.
A 1.5mm 2 cable will typically allow cable runs up to 3.3km. Table 1 below shows the
maximum cable distances given typical cable parameters.
C.S.A.
2
mm
1.0
1.5
2.5
Table 1: Maximum cable distances for typical cables
The acceptable cross sectional area of wire used is 0.5 to 2.5mm
maximum acceptable diameter of cable used is 15mm. The table is provided for
guidance only, actual cable parameters for each application should be used to
calculate maximum cable distances.

3.7 Cabling Requirement Multidrop MODBUS

This fulfils the requirements of multidrop communications back to a compatible address-
able control panel. Due to current consumption of multiple detectors powering of acces-
sories via the detector sounder/beacon output or relay contact must be avoided.
Each detector must be configured with a unique node address when connected in an
addressable network.
Power +V
Power 0V
RS485A
RS485B
Screen
Xgard Bright
Four connections are required for multidrop operation: a 24V/0V dc power supply, and
RS-485 A and B connections to the appropriate terminals. Two sets of RS-485 terminals
and a spare cable gland entry (sealed with a stopping gland by Crowcon) are provided
to enable signals to be 'looped' to the next detector easily.
(Ohms per km)
Awg Cable
17 18.1
15 12.1
13 7.4
Xgard Bright
Detectors
Resistance
Loop
36.2
24.2
14.8
Control
Panel
Xgard Bright Xgard Bright
Max. Distance
(km)
2.2
3.3
5.4
2 (20 to 13awg). The
Beacon/
Sounder
Termination
link fitted
here
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