"Thanks for the info guys. I was just curious. How bad is the accuracy?"

"Why was the compass moved externally?"

"Hi, Yes your if and else branches do the same.. that was what I meant also, except that I suggested just removing #if, #else and #endif entirely.. But OK glad it's working! Regards Soren"

"Hi Soren,        I got my system working now, but I did add one more change in ArduPlane.pde(or ArduPlane.ino) to set uart2 with Serial3 as below. #if TELEMETRY_UART2 == ENABLED// solder bridge set to enable UART2…"

"Bharat, Do you have any details on how you did this?"

"I beg to differ. On APM 1.4, APM2.5, and PX4, you can in fact have two devices sending mavlink to the board and changing stuff(why anybody would want to do that is another matter all together). For example, I use uart0/USB to connect to APM for…"

"Hi Soren,        I'd also like to have two serial ports at the same time, and with a multiplexer switching between USB and a radio. So I just comment #if, #else and #endif as you mentioned above in system.pde, and…"

"Hi, There is no way without a recompile. And you have to do: #define TELEMETRY_UART2 ENABLED in APM_Config.h . Besides that, for some reason I have never understood, there is a condition made to prevent UART2 telemetry if the multiplexer of APM2 is…"

"I am trying to add my own logger via USB (as I'm doing with an APM1.5 board), and still direct everything via Mission planner. I tried to solder Pin 6/7 (normally connected/com) of the TS5A23157 chip together and hoped that through that I can…"

"I am not sure if this is wrong place to ask this question, but it is related to using UART2 instead of UART0, the thing is that I have been using minimOSD with APM 2.0 and everything works great, then all out of sudden it stopped working (just on my…"

"This goes back to why. I'm not trying to be difficult, but this is just the wrong approach to a system. The APM and code is a work in progress and ultimately tuned for the best performance. Anything you do to modify the code does 2 things, hurt…"

"I see the simplicity in just splitting a UART, but what if you want to just send a subset of the mavlink data on the second UART?  While I could have my payload sort through the complete telemetry feed and pick out what it wants, is having the…"

"Point well taken and good info.  Most users probably don't need two UARTs.  In my flight configuration I have an OSD and an external data recorder to record durations of 3+ hours of TM.  I'm also using flash now but…"

"This is exactly what I was saying was possible, but no reason to need a second UART to do that. Most devices have low enough impedance that connecting more than one (say Xbee and OSD) were already being used by many with no problems off of a single…"

"Yes. Check out the link to the other thead I posted above. I'm doing just that, writing everything that normally goes to flash to serial2/uart2 (and then some). I am demoting writes to 3.3 Hz besides att/rate/accel/mag. Works well."

"What about using UART2 for only ouput?  I could see this being useful for payloads that want position data from the APM, while still having a fully functional telemetry link to the ground.  Is this possible?"