Telemetry Radio will not connect

Hi all,
I recently purchased a pixhawk and it came with the radio telemetry module. Initially it seemed to be working because the LEDs were solid green and the ground device would receive information on configuration from the air device.
Unfortunately i clicked on the “upgrade firmware” button in Mission Planner and i could never get a connection again. The firmware 1.9 seems to be loaded on the ground device successfully, but i am unsure what state/firmware version the air device is at.
The air device doesnt have a USB connection so i cant connect it directly to the PC.

Could it be the different firmware versions? If so, what is the stock firmware version that it ships with?
If the firmwares are backwards compatible, how can i figure out what the frequency, baud, netid are set to on the air device?
Is there any way to reset both devices to the same settings?

As an aside, i tried firmware 1.6 and 1.7 on the ground device with no success.

Thanks for your help

Is your telemetry radio a genuine 3DR radio?

Hi Paul,

The radios with different versions of firmware should at least be able to talk to each other. I’ve successfully used radios with v1.6 and v1.9.

I suspect what has happened is the NetID of the updated radio has been reset to a different number than the other. This will prevent them from talking.

In mission planner, go to Initial Setup->3DR radio. Connect your radio and have a look at the Net ID that comes up - from memory you may need to click Load settings to download the settings. Do you remember what it was before the upgrade? If that has not changed, also look at the Baud rate, it should be 57k.

If you turn the remote radio on, the settings for the Remote radio should appear, assuming the two radios are able to talk (ie. NetIDs match). If not, you will need to plug in the remote radio directly, I thought genuine v2 3DR radios had micro USB ports on both ends? If not you could still hack a cable to plug into an FTDI USB board/cable and then your computer.

The only other way is to manually try different Net ID’s from 1-255 until you get a connection, assuming NetID is the problem.

Hope that helps

Its definitely not a genuine 3DR radio if it only has a usb connection on one device.
Other than the NetID, what else needs to be identical for the link? i changed the tx power, frequency and channels.

i now cant connect or load the settings of the local ground device. i get an error saying “Failed to enter command mode”.
Is there a way to reset to defaults on the board itself?

Unfortunately this Telemetry Support Forum is for genuine 3DR products only so I am going to move your post to another Forum.

My devices look just like these: … 84349.html … 46777.html

Is it not 3dr?


Those telemetry radios are clones copied from the original 3DR Open Hardware designs.
If you did not buy them from either 3DR direct or an authorized reseller, then they are clones.
My genuine 3DR hard case telemetry radios do not look like that on the top of the radios. All they have printed on the top of the case is the 3DR logo and 915MHz.

To make them talk, the Net ID, frequency and channels should match. The tx power is not important at close range.

“Failed to enter command mode” is usually intermittent, but if you are getting it every time, then it sounds like something is wrong with the radio. Check that you have the right COM port selected in mission planner. Does the COM port show any name next to it in the mission planner combo box (eg. something like COM 7 ftdi device)? At least in that case it’s still being detected.

I own both genuine RFD900 radios (these are awesome but expensive) and some clones (these are cheap) - you just have to accept that some of the clones will be bad. I don’t know of any way to reset the board to defaults.

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