Now you’re wondering about smoke detector electrical signaling and communications system. Indeed, the picture is quite a complicated one. Is there a standard? Sort of, BACnet may be the lowest common denominator standard. It is mainly a protocol, with many different choices for the physical media and electrical signaling standard: RS-232, coaxial cable (ARCNET), RS-485, Ethernet, LonTalk (twisted pair, fiber optic, powerlines, etc.), and so on. Still, there are many proprietary protocols in use too, and other semi-standard protocols and wiring styles.
Note that BACnet is also widely used for HVAC control.
20180726/DuckDuckGo smoke detector control panel signaling standard
20180726/https://en.wikipedia.org/wiki/Fire_alarm_control_panel
Ah, great design here! You can also apply a graphical display system into your fire control panel, no need to rely on weird codes only. The LEDs can be built into the graphics diagram.
20180726/https://en.wikipedia.org/wiki/File:Potomac_hall_facp.jpg
20180726/https://upload.wikimedia.org/wikipedia/commons/4/45/Potomac_hall_facp.jpg
20180726/https://en.wikipedia.org/wiki/BACnet
Interesting, so RS-485 is like RS-422 but with amendments to switch off receivers, which enables two-wire straight line shared bus topology.
20180726/https://en.wikipedia.org/wiki/RS-485
20180726/https://en.wikipedia.org/wiki/Arcnet
20180726/https://en.wikipedia.org/wiki/LonTalk