Fire Alarm System Multi-Line and Bus System
Fire alarm system bus system instance diagram. The so-called fire alarm system multi-line refers to each detector (device) having an independent signal circuit with the controller, and the detectors (devices) are independent of each other, with all detection signals being input to the controller in parallel. In simple terms, it is a point-to-point connection. The fire alarm system bus system refers to a bus circuit formed by two or four wires, where all detectors (devices) are connected to the bus, and each detector (device) has its own independent address code. The controller generally uses serial communication to query each detector (device) by different addresses.
Fire alarm system bus system instance diagram. Currently, in China, detectors and other devices such as manual alarms, fire hydrant buttons, sound and light alarms, modules, etc., all adopt the bus system. The bus system uses fewer wires and is convenient for design and construction, thus it has been widely used. The commonly mentioned two-bus clearly refers to the bus system, which means two signal buses. The four-bus adds two power lines to the signal lines. In contrast to the bus system, the multi-line system uses more wires, has higher costs, is troublesome for wiring, and is difficult to troubleshoot. However, the multi-line system has not completely exited the stage; critical equipment in fire safety, such as pumps and fans, still requires multi-line control. This is because the stability of the multi-line system is higher than that of the bus system, and since they are independent of each other, they are not affected by other devices or circuit failures. Although the multi-line system uses more wires, the circuit is simpler and more stable, and will not cause partial paralysis or even system collapse due to a fault at any point. Both systems have their advantages and disadvantages. After development, our country is currently basically at a stage where detectors (devices) use bus connections, while linked devices like pumps and fans use multi-line connections. Multi-line fire alarm controllers are becoming hard to find; abroad, detection devices still have multi-line fire alarm controllers. According to what I understand, in China’s fire safety industry, only gas detection controllers still have multi-line systems. However, small systems are indeed quite suitable for multi-line use.