Knowledge Base

Why would I want or need an NMEA Autoswitch?

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The NMEA 0183 standard allows any suitably designed marine electronic device to share its gathered information with any other device on a vessel. Unfortunately, there is one very large drawback with this standard – only one device on a connected network can actually send data (a single ‘talker’ device), with multiple devices (determined by the current limit of the sending unit) listening to that data (multiple listeners).

Secondly, for systems that have multiple NMEA devices of an identical type (e.g. two GPS’s or two depth sounders), automatic selection of the highest priority device with valid data is normally a vital requirement. However, the NMEA 0183 standard has no method of automatically switching between different devices, so this requirement is usually fulfilled with a manual changeover switch: not a very good solution, but the only one available until now.

The Actisense NMEA Autoswitch solves both of these problems by allowing up to 4 input devices/talkers, connected through full galvanic opto-isolated inputs, to be analysed, and the NMEA data of the highest priority device automatically switched to the NMEA output.