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Phantom 2 / Futaba sbe-1 / graupner MX20

Discussion in 'Phantom 2 Mods' started by BelgiqueBasterd, Dec 15, 2015.

  1. BelgiqueBasterd

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    Hello,

    I've setup my phantom 2 H4-3D for a Graupner mx20 transmitter. Everything works well, and phantom flies ok with all the functions working.

    However one thing is not working, the phantom does not go into failsafe mode when I turn the transmitter off. Failsafe works perfectly when activated with the switch, but not when I turn off the transmitter. When I check the assistant software I see all the stick inputs return to 0 when I turn off the transmitter, but failsafe mode is not activated.

    Any ideas as to how to fix this problem?

    Setup: Phantom 2 Naza -> Futaba SBE-1 Sbus to pwm encoder -> Graupner GR24 rx -> Graupner MX20 hott TX

    Kind regards, Christof.
     
  2. pomonabill220

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    Don't think it matters, but what firmware version is in your P2?
    I would think that this feature would be in all the version though.

    A question... how do you know that failsafe is not activated when the TX is turned off? Remember, it takes a few seconds before the quad will start it's failsafe.
    Do you a FPV/OSD installed? And if so, do you see the FS being displayed in your monitor? (I am not familiar with the equipment you listed).
     
  3. N017RW

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    I cannot tell you how to fix but the way receivers handle the loss of signal varies and is programmable on some types (not familiar with the Graupner Rxs). It seems you have investigated and noticed all channels go to (output) '0' and this must be different than what the OEM Rx does.

    Until this (output) is the same as the P2's OEM Rx fail-safe will not trigger.
     
  4. pomonabill220

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    Hhmmmm... interesting info! Thanks N01!
    So the failsafe "trigger" relies on the OEM signal to "disappear"?
     
  5. N017RW

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    Well, it relies on some pre-set condition that is output from the OEM Rx upon loss of signal. Not sure disappear is the condition or best description.
     
  6. pomonabill220

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    I see... so when the remote shuts down, it sends some kind of code first?
    Would that be the same if, for instance, the antenna disconnected?
    To me, that would be loss of signal, but the remote was not shut off.

    OR, while the remote is on, it is sending some kind of "keep alive", and if the quad doesn't receive that for a preset time, it switches to FS mode... kind of a heartbeat signal that the quad is expecting.

    Just trying to get a better understanding of this situation.
     
  7. N017RW

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    Don't over think it.

    The system is digital.

    When the Rx is no longer is receiving it's signal (remember the Tx and Rx are bound together) the receiver reacts in some pre-determined way. Many systems allow the user to program or determine this reaction. I do not know exactly what the DJI system is 'looking' for at signal loss so until you do and if you can program the Graupner to mimic it you may not be able to use that feature.
     
  8. BelgiqueBasterd

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    Thanks for the reply, I will reinstall the original phantom 2 receiver in the phantom and then see what happens in the DJI assistant software when I turn of the original transmitter.

    I'll then try to duplicate the action using the graupner transmitter. How long should it take after the transmitter is turned off, for the phantom to go into failsafe mode?

    To be continued :) !
     
  9. N017RW

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    Great idea.

    I don't recall the exact amount of time to react.

    Let us know what you find out.
     
  10. BelgiqueBasterd

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    I have another question, in the assistant software what do the numbers next to the stick, u, x1 and x2 input stand for?
     
  11. N017RW

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    Not sure what the unit is but it is an indication of the amount of channel input.
     
  12. BelgiqueBasterd

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    It works! I reinstalled the original phantom rx and then tested to see what happens when I turn the original tx off.

    All inputs stay in their last position before I turn the tx off, only the U (S1 switch) channel input changes to 471 and activates the failsafe. I then dug into the manual of the graupner TX and it's possible in it's failsafe menu to choose 1 channel and set the input value to whatever I want. So put the U channel to 471 and now it works perfectly, it switches into failsafe the instant I turn the transmitter off.

    Thanks a lot for the help and explanations! Very nice and knowledgeable forum this is!
     
  13. pomonabill220

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    GREAT that you got it working!
    Also nice to know if others plan on doing the same thing.
    thanks