Bosch 3.5 ユーザーズマニュアル

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Bosch Security Systems | 2011-02
Praesideo 3.5 | Installation and User Instructions | 7 | System Hardware Installation
en | 303
controller. The standard EN 54-16 requires a minimum 
sound pressure level of 60 dB for the voice alarm 
condition and 50 dB for the fault warning condition, on 
1 m distance, even with the door of the rack closed.
The Praesideo PRS-NCO-B is delivered with a suitable 
buzzer for these purposes. This buzzer needs a power 
supply with backup. Although the system network 
supply could be used for this purpose, the power supply 
lines of the hybrid network cable are not easily 
accessible. Another option is to use the RS232 
service-connection on the rear of the network controller. 
This connection is never used in an installed system, so 
it is possible to take advanrtage of its availability. An 
output voltage is available on pin 6 (DTR output) that 
switches between -9V and +9V, while pin 5 provides a 
GND connection. Using a high efficiency buzzer and a 
rectifier bridge, the RS232 connection can provide 
enough power to drive the buzzer to the required sound 
pressure level. Control outputs are located on short 
distance of  the RS232 connector, to provide the 
switching information. See the wiring diagram in figure 
32.5.
In this arrangement, the voltage between the RS232 
DTR and GND connections is rectified and wired to the 
buzzer. The negative lead is interrupted by control 
outputs 3 and 4, connected in parallel, configured as 
follows:
NCO_CO4 is enabled and configured as Fault alarm 
buzzer
 (by default, cannot be changed, see section 
43.2.6)
NCO_CO3 is enabled and configured as Emergency 
alarm buzzer
 (see section 43.2.6)
NCO_CO3 and NCO_CO4 are connected in parallel. 
The C-terminals of both control outputs are 
interconnected and the NO-terminal of NCO_CO3 is 
connected to the NC-terminal of  NCO_CO4 to switch 
on the buzzer in case of an emergency alarm or fault 
alarm. The NC-terminal of NCO_CO4 is used instead 
of the NO-terminal because this control output is 
operated in an opposite mode for fail safe reasons. The 
unpowered (!) state represents the fault situation, as is 
the case for NCO_CO5, the fixed control output for the 
Fault alarm indicator.
The buzzer supplied with the network controller is 
connected to an RS232 connector, with build-in rectifier 
bridge, by means of a 2 m long cable. This allows the 
buzzer to be positioned in the 19-inch rack, on such a 
location that the required audio levels are attained. The 
RS232 connector also provides a short control cable 
that can be connected to the NCO_CO3 and 
NCO_CO4 contacts, as shown in the figure.
figure 32.5: Connecting an alarm buzzer to the 
network controller