This Railway Signaling example uses one Two Relay Controller to operate two block signals. A block signal accessory is placed at the beginning of an isolated outside-rail track block. The track block can be of any length, but is usually of train-length or longer.

Block signals are shown, but overhead signals or semaphores can also be connected. Three-light block signals can be operated by connecting the "yellow" light of a signal to the "red" light of the signal two track blocks ahead.

With no train in the block, block signal lights are "green." When a train moves into a block, the block signal changes to "red."

Power for the 2RC is supplied with a 12-14 volt accessory transformer. Outside-rail input power is supplied by the train/center-rail transformer.

The 2RC jumpers are set for the "Eight-Features Feature Set," OFF/ ON Features, and "short" input hold time. (No jumpers).

The isolated outside-rails are connected to a 2RC input. Corresponding relay terminals are connected to the block signal's lights. The relay C terminal to accessory power. The relay NC terminal to the "green" light and the relay NO terminal to the "red" light. Block signal "common" posts are connected to accessory common.

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