Telemetry Port Setup for Pixhawk and PX4

This article shows how to enable the second telemetry port on Pixhawk and PX4 and configure the ports in Mission Planner.

Note

Support for the second port was added in Copter 3.1 and equivalent Rover/Plane firmware.

Enable 2nd Telemetry Port on Pixhawk

On a Pixhawk there are two 6 pin DF13 serial ports marked as “telemetry” (TELEM 1 and TELEM 2). Both ports will be active for communication.

Use TELEM 1 for higher power devices (up to 1A), such as the 3DR RFD900 telemetry radio.

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Enable 2nd Telemetry Port on PX4

On a PX4v1 you can enable the second telemetry port by creating a empty file named uartD.en in the APM directory on your SD card. This changes the 5 pin DF13 (FMU USART2) connector on the corner of the PX4IO board from being 3 PWM outputs to being a second telemetry port.

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Set-up through the Mission Planner

The telemetry port is configured using parameters, which you can edit though your GCS. Using Mission Planner open the Config/Tuning | Full Parameter List page.

The parameters to change for each port are listed below. These are documented with the parameter in Mission Planner and in the Parameter documentation on each wiki:

  • Telem1: SERIAL1_BAUD, SERIAL1_PROTOCOL, BRD_SER1_RTSCTS
  • Telem2: SERIAL2_BAUD, SERIAL2_PROTOCOL, BRD_SER2_RTSCTS
../_images/MP-Serial2_protocol.png

You can also set the desired stream rates for messages on the ports (the telemetry rates to zero to try to keep CPU loads down) by setting SR1_* and SR2_* parameters in the Advanced Parameter List. Due to CPU resource limitations, the actual rate of the data sent and saved may be lower than the rate requested.

The data can also be changed in the Mission Planner’s Software | Planner screen’s Telemetry drop-down.

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Warning

If you change the rates using the REQUEST_DATA_STREAM MAVLink message Copter DOES NOT save the rate changes and they will not persist over a reboot.