You want to use this spreadsheet to convert between Garmin Switch Numbers and NMEA Instance and Channel numbers.
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The Evolution of the Connected Boat is Here. MPower®, from Maretron, a Carling Technologies Brand. The new MPower® Digital Switching Platform delivers simple, intuitive control over the increasingly complex systems found on today’s vessels. The result is a safer, more enjoyable boating experience. We are your ONE source for creating the intelligent boat ... from cables and connectors to complete vessel monitoring and control solutions.