There are many ways to use an Arduino on a model railroad. These tiny, inexpensive, programmable computers can perform functions such as controlling signals, routing turnouts, and running animations.
The next question is "Serial port". However, as is stated in at least one of your web pages, no modern MACs have a serial port. The Web page "Connecting JMRI to a Digitrax DCS240" says in its first ...
The AnyRail program can export a track plan to a JMRI PanelPro XML file with a Layout Editor formatted Panel. This script will create a new occupancy Sensor for each exported Block. For more details, ...