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Thread: Serial Port Questions

  1. #1

    Serial Port Questions

    I have a AFS 5500 BB:7 single screen that I am installing. I am realizing that I will run out of serial ports. The screen has the Red Box remote AHRS. Current hardware I have:

    1) VPX Sport
    2) TruTrak AP
    3) Tt22 transponder
    4) ARINC adaptor

    I would like to install the following:
    1) GTR200B
    2) Val 2KR

    I am assuming that if I use the SV network and purchase the SV Transponder and the SV ARINC, which would still leave me over the number of ports I need. I am thinking I need to buy another screen for the serial ports. I guess I could put a remote head on the transponder, but given I need to use the serial ports for the VPX and the AP, I am not sure the best way to go. Any recommendations?

  2. #2
    How did you acquire a TT22 without the remote head? The Dynon SV-XPNDR-261 does not communicate over SkyView; it requires a serial port. Moreover, the TT22 transponder is fundamentally the same as the Dynon, just with different software to allow the Dynon to function as a remote unit, whereas the TT22 requires Trig's TC20 control head.

    So, even after swapping to the SV-ARINC-429, you're still short one serial port. Many ways to make this viable:

    - replace the AFS red box AHRS and internal EFIS airdata with the SkyView ADAHRS-200
    - put a TC20 head on your transponder, which, if it really is a TT22, it probably needs anyways.
    - replace the radios with a Val NAV 2000 + COM 2000, which combined can emulate a single SL30, or replace with a GNC-255.
    - add a second EFIS screen
    Last edited by Jonathon; 10-05-2020 at 10:03 AM.

  3. #3
    Transponder is from a dual screen 5600 system that wouldn't fit in my current project. Was hoping to use parts of that system on this build, but sounds like the transponder should stay with that system. So if I go with an SV-ARINC-429, why do I need to swap out the RedBox? I though that was connected with the "compass" on the main EFIS connector. I can get a standalone transponder that does not need a serial connection, and if I go with the remote mount Val solution for NAV/COM, serial ports would be:
    1) VPX
    2) TruTrakAP
    3) SL-30 (Val NAV and COM 2k)
    4) AF-GPS

    I was having difficulty finding in the manual how you wire the SV network into the system. Does this require a serial port as well? Sorry if these questions are novice.

  4. #4
    If the transponder was purchased with the 5600 displays then it is almost certainly an SV-XPNDR-261. There is no causal relationship between upgrading to the SkyView ARINC and needing to upgrade the AHRS. The reason that I proposed you replace the red box AHRS with the SV-ADAHRS-200 in one of the scenarios is because it is one possible way to free up another serial port.

    Now you are also listing an AF-GPS (same as Dynon SV-GPS-250). You did not disclose this on your first post. If you want to run a second GPS, you are now two serial ports short. So you will need to free up two serial ports, i.e upgrade to SkyView ADAHRS and consolidate your com and nav radios, etc. etc.

    I'm not sure if the Val SL30 emulation works with their remote radio; I believe that might only be possible when their two panel mounted units are linked together.

    EFIS wires into SkyView network through the EFIS expansion harness wiring:


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    The 9 pin plug on the EFIS expansion harness needs to plug into a 5 port SkyView Network Hub, any of the remaining four ports of which can then be used to plug into the SV-ARINC-429, SV-ADAHRS-200, etc. etc..

  5. #5
    I do not need a second GPS. I was following the manual v15.1 page 93 for installing the AF-GPS on a v7 system. I currently do not have a GPS source. Sounds like I need to do some homework and come back with a better informed question. Thank you for the above post as I could not find the SV network in the expansion port in the manual.
    Last edited by R7237; 10-05-2020 at 03:41 PM. Reason: Incomplete post

  6. #6
    Small point, but took me a while to figure out the mobile site for the forum does not support the asterisk as my post kept getting truncated and took me a while to figure out. Ie: Do not as opposed to don*t

  7. #7
    Verified with Val Avionics that I can daisy chain the NAV 2KR and the COM2KR as SL-30 format on one serial port.
    GPS source is my problem with the number of serial ports left. So, looks like
    1) VPX
    2) TTAP
    3) SL-30 (NAV/COM 2KR)
    4) Transponder and GPS175 sharing the final serial port.
    System will need SV-ARINC.
    From all that I can find, the SV-GPS-2020 would require a serial port, and therefore if I want ADS-B out, I need a GPS source that would support that.
    Seems like this would require me to get a GPS175, but would allow me to keep the transponder and have everything integrated.
    I think I am getting closer to figuring it out. Please let me know if this makes sense.

  8. #8
    You cannot share the Transponder serial port, the Dynon TT22 requires both transmit and receive lines.

    Are you installing an ADSB receiver? that will also require a serial port.

    The AF-5000 will work with a SL30, GTR200 or GTR255. I believe we have seen problems with the VAL not correctly using the SL30 data format, it might not work with the AF-5000.

    The advantage of using our GPS-250 is that it will work using the EFIS backup battery in case of an electrical failure.

    The AF-5000 has 5 RS-232 serial ports and the separate Dynon SV-Network. I would highly recommend using the Dynon devices that connect using the SV-Network ( SV-ADAHRS-200, SV-ARINC, SV-AP-SERVOS ) to free up serial ports.

    Assuming you want to keep the Trutrak Autopilot this is what I would do:


    EFIS Serial Port - Device Connected
    ------------------------------------------
    0 - TruTrak AP
    1 - VPX
    2 - Dynon TT22 Transponder
    3 - Dynon ADS-B Receiver
    4 - GPS-250

    SV-Network Connected Devices
    ------------------------------------
    1 - SV-ADAHRS-200
    2 - SV-ARINC > GPS175 or IFD-GTN


    If you must have a NAV radio you should get an Avidyne IFD-440 or Garmin GTN-650.
    If you used the Dynon AP Servos you would have a spare serial port.

    If you add a second AF-5000 EFIS you would have 5 more serial ports to use.
    Rob Hickman
    Advanced Flight Systems Inc.

  9. #9
    Thank you very much for the response. This helps greatly. I should probably just buy another 5500 from you and gain the extra ports. Your response is just one example of why you are extremely deserving of the Hall of Fame.

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