This design approach uses a single microprocessor motherboard that allows for multiple interface cards. The mother board includes a pic24 with Ethernet controller.
The interface cards are identified with a microchip uni/o memory device.
This ui/o part consumes one pin of the connector. Once the card is inserted the cpu reads the daughter card and runs the appropriate code for either the power distribution, 10 serial mux port, opto isolated input and traffic control phase detection cards.