The two turnouts/switches are controlled by DCC commands from the Arduino Base Station. The Wabbit, a stationary decoder, receives the DCC commands, controls the direction of each Tortoise slow motor which clears or throws each turnout. The Wabbit and Tortoise are by CIRCUITRON, INC. The turnouts are part of the Micro Engineering Ladder Track System.

The interconnection of the elements is shown below. Most of the related wiring is routed through the custom I/O Board. The Tortoise includes two SPDT switches. One switch is used to control the polarity of the related powered frog and the other switch changes the color of a red/green bi-color LED signal light. Due to the slow switcher speeds and the short wheelbase of the switcher I wired a 'hot' frog to avoid the engine stalling on the turnouts. 

The dashed arrow between the Tortoise and Turnout is the mechanical connection.

Diagram showing connections betweem elements controlling the turnouts

The wiring of the custom I/O Board replaces point-to-point wiring with cables and plugs. The single I/O board handling the wiring for both turnouts. The plugs for the red/green LEDs and between the Tortoise and frog are symmetrical. In this way if the color of the LED or the polarity of the frog is incorrect, simply unplugging, rotating and plugging in the correct cable will correct the problem. Rewiring not required.

Wiring diagram for the custom I/O board

Custom I/O board showing plugs 

The two terminal blocks input 5VDC (+5VDC marked), and the DCC signal. The 5VDC powers the red/green LEDs. The DCC signal provides commands and power to the frogs and the Wabbit. The terminal block on the top of the board connects, one DCC wire, to the frog of each turnout. the 2-pin connector (black) at the top of the board provides the DCC signal to the Wabbit for decoding.

At the top the vertical 3-pin connectors connect to one of the tortoise SPDT switches selecting the polarity of the DCC signal sent to one of the frogs. The horizontal 3-pin connectors on each side, connect the other tortoise SPDT switch to a red/green signal LEDs.

Detailed cable wiring is shown. Notice the crossover wiring from the tortoise. This makes the two cables/plugs to the I/O Board symmetrical.

Turnout cable wiring.