Is each module box of the fire alarm system an independent loop?

A solid red dot indicates that the device is connected to the line.

In the figure, when the broadcast line is connected, it is actually all the way, but because the module control is separated in the central control room, two broadcast modules can be controlled to ring separately when in use.

Because of the low power of some devices, the bus is used as a positive and negative two-wire loop, which can not only transmit signals, but also supply power. For bus wiring, it can be understood that all devices can be connected in series on the bus. (Please note that there is an upper limit on the total number of series connections)