UM0272 datasheet(7/40 Pages) STMICROELECTRONICS

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UM0272

System features

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Special inputs are also available on the CU board such as the Tamper line used to indicate

any tampering with the system. This line is normally connected in series with the Tamper

inputs of each sensor or device connected to the CU. A fire/smoke line is also present on the

CU board and is used to continuously monitor all fire or smoke sensors; immediately

signaling any warnings depending on the line configuration, but independently of the CU

status.

The system works using an RS-485 communication bus. This is a 4-wire bus (2 wires for

power, 2 for communication) that complies with RS-485 standards and guarantees good

noise immunity. The communication algorithm provides an encrypted protocol that prevents

information sniffing on the communication bus. Thanks to this bus, system modules can be

placed far away from the CU using a reduced number of wires. This configuration reduces

setup time, wiring and the wiring costs.

Figure 1.

System overview

UM0272 Datasheet(PDF) 7 Page - STMicroelectronics