Why would I want or need an NMEA Autoswitching?

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.

Our current range of multiplexers and our PRO-BUF-2 have autoswitching capabilities, where the priority can be defined. The NDC-4 has ‘smart’ autoswitching, which means that as soon as the data is identified as invalid or corrupt it will switch to the secondary input. The NDC-5 and PRO-MUX-1 / PRO-BUF-2 are having this feature added in the future, as they currently autoswitch when no data at all is present on one input.

For more information on NMEA 0183 and how it works, please download our free guide to NMEA 0183 networking here: https://actisense.com/everything-to-know-about-nmea-0183-guide/