"Solution was the same as Tony M. TX solder joint looked fine, but somehow was not making a connection! I re-soldered it and all is well!"

"I have the same problem. Brand new APM2.5 and 3DR radio pair. Someone doesn't know how to spell "were"... "

"I had exactly the same issue. I resolved it changing the USB 3DR radio to COM3: As my APM USB connection used to use the COM3: the 3DR starts using COM4: I went to Windows Control Panel and opened the device manager. In Ports properties, I changed…"

"I also have a similar issue with APM 2.5  stating "No HeatBeat Packets Received".  However I was successful with a connection, then without changing any settings and trying to reconnect, I'm back to the same…"

"I changed the code on line 177 to "const float AP_InertialSensor_MPU6000::_accel_scale = 9.81 / 2048;" But i'm not sure how to change the code within Lines 444 to 458. I'm not quite sure what those lines are actually doing."

"I did! Thanks for the help though. You were right, one way traffic. Bad soldering on my part apparently. Re-soldered and it works like a charm."

"Thanks Randy.  I did end up loosing the attitude matrix on the last flight, but looking at the gyro limits in the code sections you mentioned show 2000 d/s is already in play (the max).  On the way down I experienced a 4g barrel roll from…"

"sounds like you are only getting traffic one way. ie the apm is sending, and the pc is receiving, but anything sent to the apm is failing. Try putting the remote 3dr radio into a loopback mode, by plugging in the tx to the rx on the remote modem.…"

"Ah excellent news.  I just got my 3dr radio today so if i stumble across this issue I'll know what to do!"

"Rechecked as well, no chance to get it work. when micro USB plug is connected, the TX/RX leds are blincking. when powered by battery and want to connect via radios not  a single blink . Comm 3 dead? b.r. Wolfgang"

"I got it guys. Turns out that the TX pin on the 3DR board didn't actually get soldered. The solder wasn't inside the hole, its so small i couldn't tell. Which makes since because I was able to connect to the APM and recieve the…"

"Got it! Turns out that the TX pin on the 3DR board didn't actually get soldered. The solder wasn't inside the hole, its so small i couldn't tell, so it wasn't ever actually connected to the 3DR board. Which makes since because…"

"Got it! Turns out that the TX pin on the 3DR board didn't actually get soldered. The solder wasn't inside the hole, its so small i couldn't tell. Which makes since because I was able to connect to the APM and recieve the telemetry it…"

"forgot: red leds on both radios are flashing twica a second, grenns always on. It seems that the led of radio connected with computer is more dim than the other one. b.r. Wolfgang"

"Gentleman Same problem on 433 Mhz ones, same settings only AP 1 with 1280 please help many thanks b.r. Wolfgang"

"Gentleman using the APM1 with 3DR radios, same problem! Can read 33 packages but no param packets where received Kindly ask for help many thanks b.r. Wolfgang"