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. Each 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, a 'hot' frog is used to avoid the switcher stalling on a turnout. 

The dashed arrow between the Tortoise and Turnout is the mechanical connection that moves the turnout points.

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 4-pin terminal block input the DCC signal and 5vdc (-vdc is marked). The 5vdc powers two red/green LEDs one for each turnout. The DCC signal is connected to the frogs and Wabbit. The 2-pin blue terminal block on the bottom edge of the board connects, one DCC wire, to the frog of each turnout. the 2-pin black connector provides the DCC signal to the Wabbit for power and decoding.

Custom I/O Board showing wiring.

On the left and right sided the vertical 3-pin connectors connect the DCC signal/power to one of the tortoise's two SPDT switches which selects the polarity of DCC power sent to the appropriate frog.

Circuit board holding red/green LED, resistors and plug.

 In the middle of the board the horizontal 3-pin connectors, connect +5vdc to the other tortoise SPDT switch. Depending on the position of the Tortoise, and therefore the turnout, +5vdc is connected to the red or green signal LED through the 3-pin receptacles along the top edge of the circuit board.

Thee small boards hold the red/green LED and the two resistors to control current. The resistors are on the board with the LED so that the correct resistor stays paired with each color of the LED even as cables are rotated. Notice that the green side of the LED is four times as bright as the red.

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.