The On Guard auto-reverser (OGAR) can be used to automatically route power to the frog(s) of your switches. In addition to the auto routing of power, it also provides a circuit breaker function to protect the switch and your equipment in the event of a derail on the frog. The OGAR has two outputs: Rail 1 and Rail 2. Rail 1 connects to DCC 1 in normal and DCC 2 when the OGAR is reversed. Rail 2 connects to DCC 2 in normal and DCC 1 when the OGAR is reversed.
Note that when the OGAR senses a frog in the wrong polarity, BOTH outputs reverse. This is because the OGAR is originally designed as a reverser, but a frog controller is simply a one rail reverser. Because the two frog outputs work together, the OGAR can’t be used to control two frogs that the train can hit at the same time, since that could cause a conflict as to which direction is required. This is not as much of a limitation as it may seem because usually frogs that can be touched by the train at the same time are in a switch route. Hence, for the given route, you can predict the polarity required of each frog. Start with the first switch and pick, say, the Rail 1 output. For each switch in the route, decide if it is in phase or out of phase with the first switch. If in phase, connect the frog to Rail 1. If out of phase, connect the frog to Rail 2. Now, when the first frog is touched, all the frogs in the route will be correct. Each switch, if crossed individually, will still flip its frog to the correct phase as required.