Little help interfacing an Apollo GX55 with ELT

Discussion in 'Avionics and Upgrades' started by Eric Lehto, Mar 13, 2020.

  1. Eric Lehto

    Eric Lehto Pre-Flight

    Aug 5, 2018
    Antelope Valley, CA
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    So my old 121.5 ELT is due for a battery replacement, so I figured I'd just upgrade it to a new 406 model at annual next month. I then figured that since I'm going through that much effort, it wouldn't hurt to feed it position via RS-232 from my ancient Apollo GX55 GPS. I just want to make sure the ELT is properly configured.

    I found an old GX-55 installation manual online, and it's RS-232 specifications have TX formats of Moving Map (MOVMAP) and Nav-Comm (MAPCOM). They are both
    Baud rate: 9600; Data bits: 8; Stop bits: 1; Parity: none.

    Meanwhile, the Artex 345 ELT in particular requires Aviation Protocol baud rate 9600 or NMEA 0183 baud rate 4800.

    Is it safe to assume the Apollo MAPCOM protocol is the same as the Aviation Protocol 9600 baud? Obviously I am not an avionics tech, just an owner that likes to know his stuff before talking to his MX.
  2. asicer

    asicer En-Route

    Jan 1, 2015
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    Usually yes. If the pins are hooked up correctly, there's no harm in trying both GX55 options and seeing what works. That is assuming you have a way to determine pass/fail on the ELT side, though.