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Fault Finding of Data Transfer Faults
General Information
The following components of the smoke detection system SDS are connected by a 4-
wire-bus ( RS485-bus ):
Name of Component
Indication- / control module
in smoke detection panel
Detector interface module
in smoke detection panel
Detector interface module
in extension unit no.1
Detector interface module
in extension unit no.2
Indication- / control module
in repeater panel
The master calls successively all slaves to send data ( for example: status of smoke
detectors and airflow indicators ). This data will be read and displayed by the master
and by the repeater panel.
Each slave has an adjustable address-no. The address no. of a component serves for
internal and external identification of a component.
In case of a fault the component with the address "x" will be displayed as "Device –x-
" on the LC-display.
The no. of slaves to be called by the master must be adjusted by a rotary switch at the
rear side of the indication- / control module in the smoke detection panel.
The bus cable supplies electrical power for the slaves ( 24V DC ) and is used for data
exchange between all modules. In all components, the terminals for the bus cable are
labeled with the same terminal-nos.:
Terminal-No.
17
18
19
20
All components must be connected by the bus cable in a line ( not in form of a star ! ).
At both ends of the line the bus must be terminated with a resistor 120 Ohm. In most
cases one of the ends is in the repeater panel, the other end is in the smoke detection
panel or in the last extension unit. The sequence of the components within the line
needs not to follow the sequence of address nos.
Fault Finding Instructions SDS26
Function
Master
Slave
Slave
Slave
Slave
Next successive no., depending
from no. of extension units
Function
Power Supply +24V DC
Power Supply 0V
Data Bus Signal A
Data Bus Signal B
16.06.09
safetec
Address – No.
No address
1
2
3
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