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Thread: FADC vs ARNAV

  1. #1

    FADC vs ARNAV

    I noticed in the 5000 installation manual the serial port setting for a GTN-650 is AVTN/FADC1.

    I had the GTN-650 configured as AVTN/ARNAV on my 4500 and everything worked fine. I was wondering whether I should change the configuration on the GTN as well as on the 5400 to AVTN/FADC1 (is there any advantage)?

  2. #2
    Yes, you should change it. FADC1 sends altitude data to the GTN so it can auto sequence departure procedures.
    Rob Hickman
    Advanced Flight Systems Inc.

  3. #3
    Since upgrading I now get the following Message on the GTN 650 - DATA SOURCE Pressure altitude source inoperative or connection to GTN lost.

  4. #4
    You don't have the GTN650 or EFIS configured as FADC1
    Rob Hickman
    Advanced Flight Systems Inc.

  5. #5
    I think I have it correct. On the EFIS I have serial port #2 function set to AVTN / FADC1 and on the GTN I have RS232 2 input set to FADC Format 1 and output set to Aviation Output 1.

    On the transponder inputs/outputs I have the RS232 Config set to port 2 input Altitude Format 1 and output Off.

  6. #6
    Are you positive that the EFIS serial port #2 is wired to the GTN serial port #2? TXD and RXD?
    It sounds like the TXD from the EFIS is not wired to the RXD of the GTN.

    What transponder do you have and where is it wired?

    I highly suspect it is not wired like you think it is or has a broken wire. Have you tried using the diagnostics menus on the GTN-650 to see what data it is getting?
    Rob Hickman
    Advanced Flight Systems Inc.

  7. #7
    We had another customer with a very similar problem, after weeks he found that he had a TXD line from his transponder also connected to the TXD of the EFIS.
    Rob Hickman
    Advanced Flight Systems Inc.

  8. #8
    I checkd the GTN RS232 diagnostic...I am getting a data feed..the string is ALT 00640.ALT 00640...

    This would appear to be correct. When I switch back to ARNAV I no longer receive the error message.

  9. #9
    Are you running the latest software on the EFIS from our web site?

    Are you sure you have the serial port on the EFIS configured for FADC1?

    We have this working on lots of customer planes, including my RV-10 so something is strange with your setup.

    email me pictures of the EFIS serial port configuration and GTN-650 configuration.
    Rob Hickman
    Advanced Flight Systems Inc.

  10. #10
    When you switch the GTN-650 back it is no longer looking for altitude data and will not have an error.
    Rob Hickman
    Advanced Flight Systems Inc.

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