Iris + won't arm

I have an Iris + using a Spektrum satellite and DX9 radio. I can only get the Iris to arm and motors run when the Iris is connected to my computer via USB (plus with LIPO plugged in of course).

If I go through this procedure without the USB cable attached, The Iris will initialize, LED will blink green, safely button pushed, stick right down on radio, LED changes to yellow and alarm goes off. It will also turn from blinking green to yellow without attempting to arm if I just leave if for a short time.

As I say, no problem if the USB is attached.

I would be most grateful for some help with this.

Many thanks


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  • When I have it connected to the computer via USB, with or without MP open and connected, the Iris will arm so there is no error message on the flight data screen.

    However, prior to getting to this point I have had the error message 'Prearm : GPS speed error'

    Thanks for your response.

  • If you have it connected to your computer, and run Mission Planner, it should give you a message as to why it will not arm.

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