How use CAN bus in elevators?
CANBus is a physical network layer, take vehicles for example, instead of running wires long distances, you will have a device e.g. the ECU take in most of the signals nearby to it, digitize them, and send that as data to any other nodes that may need to make use of that data.

E.g. the transmission needs to know the throttle position and RPM and load to cleanly switch gears, instead of trying to connect all those signals to the transmission by wires, the ECU digitizes them, as that information is already being used there and then shares that information with other nodes about the vehicle on a pair of CANBus wires. reducing the loom complexity for a slight increase in end point complexity

In an elevator, you might break it up into a few systems using less wires, e.g. the entire switch panel in the elevator, all those switches do not need wires running back to a controller in the pit, they can be digitized locally and send down a single CANBus to the pit, equally for the motor controller, the speed, correcting for positioning errors, etc, can all be communicated between the nodes on a network like this, just leaving the critical signals like E-stop or similar to have a secondary dedicated path in a case where something goes wrong,

That is one of the main downsides to this approach, a short of the bus at 1 node can disable an entire chunk of the network, so you need to offset the wiring simplification with some programming complexity to handle how to fail safe in all conditions.