The SHD2 is a dual signal head accessory decoder. This affordable decoder can handle 2 signal heads (4 aspects each) with simple wiring. It is compatible with JMRI Signal Heads and with Digitrax Signal Masts. It connects to your DCC power bus.
Don’t get me wrong, signaling is still fairly complicated, requiring block detection and a computer running your favorite software to control the signal logic, but the SHD2 has simplified it a little. This is a great way to add signals to an existing Digitrax signaling system without the expense of another Digitrax SE8C. It is also a great component to use in a new signaling system on your layout.