Bio photo

Dan Nixon

Code Monkey, Electronics Engineer, Mad Scientist.

Hourai RC logging tools

By Dan Nixon on 2016-07-07

Ever since I started using a radio that supports OpenTX (initially this was a 9XR-PRO, I upgraded to a Taranis at the start of the year) I've been looking for an easy way to log the time I spend using various models.

For a while I did use a basic text file based system that was kind of machine readable, however adding new entries and viewing historical logs was an utter pain. For this reason I decided to design a new logging format that would address a lot of these issues.

The main requirements were:

  • Machine readability
  • Ease of adding new logs
  • Ease of viewing old logs
  • Possibility of automation

These requirements saw the creation of Hourai, a JSON based logging format for models, maintenance and sessions.

The format form the JSON files are given by two schemas:

  • The model file, which contains general information about a model and its maintenance log (model.json)
  • The session file, which contains information about the time, location and weather conditions of a session as well as the models that were in use and any incidents (session.json)

JSON was a natural choice due to the wide range of parsers and generators available for the format, which ticks off the machine readability and automation requirements. It being a text based format it also allows it to be easily version controlled.

I then used the json-editor library to take the JSON schemas from Hourai and use them to create a web based editor for the JSON files; Hourai-Editor.

The editor (available online at allows easy editing of model and session files and saving/loading from the local disk. Compared to my old method of logging this is by far a much simpler method of manipulating the log files and having in built validation ensures that the data is always kept complete and intact.

I've started working on a telemetry script for OpenTX that will automatically generate the session JSON files on the Taranis, hopefully this should be finished in a week or so when I am less busy.