Bosch Appliances 3.5 manual

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.

figure 32.5: Connecting an alarm buzzer to the network controller

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.

Bosch Security Systems 2011-02