OTXSIM debugging tool



Tired of having to assemble the model when designing a setup? OTXSIM is a graphical tool for designing and validating your setup - without the need for the model. It runs in the Companion sim, using a profile for the Taranis X9D.

OTXSIM displays a live presentation of the active model. Virtual control surfaces respond as you move the 'sticks' in the simulator. The travels are derived from the mixer (not output) values, making it easy to spot bugs in your mixing scheme. Using OTXSIM, it's possible to design and test the mixers without the model being present. (The model will of course be needed for the final outputs calibration).

All common glider layouts are supported. By following a simple naming convention for the outputs, OTXSim can configure itself automatically.



OTXSIM version 1.3 (29 Dec 2021)


  • OpenTX Companion 2.2 or higher
  • EdgeTX Companion 2.8 or higher


  • Script (right-click, save as)


  1. Download the script, and change the file extension from '.txt' to '.lua'
  2. Copy the script into the \SCRIPTS\TELEMETRY folder of the SD Structure path (specified in Companion settings).
  3. Start Companion and select a profile for X9D/X9D+
  4. Open an .otx file and select the target model.
  5. In the Telemetry menu, scroll to bottom, set the first screen to 'script' + otxsim
  6. Save the .otx file

The screen definition for OTXSIM is now saved with the model.


To run the script:

  1. Start Companion and select the model
  2. Start the OpenTX simulator
  3. From the splash screen, press {long PAGE} until OTXSIM is displayed.


Drawing conventions

The surfaces are drawn using the following convention:

Individual surfaces can be shown reversed (see the Configuration page).

Auto configuration

At startup, OTXSim looks at the channel names and makes an informed guess as to their function. For example, a channel name containing 'v' and 'r' is mapped to the right V-tail panel. Suggested control surface names for auto-configuration:

If the auto configuration fails, surfaces can be manually assigned in the configuration page.



OTXSIM is designed as a development tool. If running on the tx, it's recommended to remove it from the final setup before flying.