Hello Folks just joined Dronetrest and trying my first build . I have a Mamba 405 MK 2 30A stack that is having issues with the XM+ not communicating with the reciever . The reciever is bound but nothing happens in the reciever tab in Betaflight . Yes the battery is plugged in . Any advice would be appreciated , Thanks !
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Welcome to Dronetrest then.
Lets see here,
Would your FC by any chance happen to be the MAMBA F405 Mini MK2?
Because you mentioned 30A. But not important at the moment.
So receiver is bound so I presume you connected the wires correctly to the FC, black to ground, red to 5V and the (usually) green wire to the SBUS pad of the FC.
Make sure that wen you turn on the transmitter and power up the receiver you see the green led, indicating the receiver receives commands from your transmitter.
Next step, BF.
No need to plug in your battery, unless your receiver isn’t powered by the USB connection.
Configuration tab - Receiver. Serial based Receiver and SBUS.
It should look like this.
Save & Reboot if u made any changes there.
Next, Ports tab.
Activate “Serial RX” for the UART 1. Default for most Mamba 405 boards is UART1 for SBUS.
Again Save & Reboot.
Check if the correct settings are still in place on both tabs and if so, try the receiver tab and all should be ok.
Goodluck en let me know if when that didn’t help.
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Hi and thanks for geting back to me . Yes I wired it according to diagram , and it is the mamba 405 mk2 30A . I did try all that and the reciever is a solid green . Zero response on the recievers tab or the FC . Been choked for about 3 weeks now 
that these people dont install the right firmware before selling them .
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That would have been my next suggestion.
To check firmware version of Transmitter and receiver. They should be the same.
Yeah that would be nice to have it always shipped with the latest firmware.
But will never happen simply because imagine the seller having 100 transmitters in stock.
Has to open all boxes to update the firmware whenever a new version comes out while in stock.
I for one get suspicious when I receive an opened box or FC with broken factory seal.
I read somewhere on youtube someone with the Rxsr reciever was having the same issue with thd 405 and it turned out he held his bind button down too long and it switched the reciever into some other mode . I have xm+ but maybe its a similar problem . I just ordered a radiomaster T16S TBS package , which should be here in early June . So hopefully the binding nightmares with taranis will be a thing of the past .
True, i read that one to.
I wonder if it is specified in the manual how long the button should be pressed.
I am having the same problems do you fix it ?