Introduction

FlightVars is a Flight Simulator/Prepar3D plugin that exports the internaldata of the simulator to the outside world.

Sometimes the addons running in your simulator are not enough. In somesetups, there are pieces of software that must run outside the sim. That'sthe case of some peripherals used in simulation cockpits, or some addonsthat, for any reason, must run as stand-alone processes outside the simulator.When that happens, we need some kind of interface between the sim and theperipherals so the latter is able to see and alter the state of the simulation.

If you are familiarized with SimConnect or FSUIPC, you've got the idea.FlightVars is aimed to solve a similar problem with a different approach.

• Performance. Retrieving data by polling is the past. FlightVarsis powered by MQTT, a lightweight, binary protocol specifically designedfor telemetric systems. Its reactive programming model joined to itsasynchronous IO architecture provides the best performance you may have.

• Interoperability. Forget about limiting your addon to the platform andprogramming language you didn't choice. FlightVars is powered by MQTT,a standard protocol with multiple implementations and large vendor support.The only thing you need is one of many MQTT client libraries available in themarket for your favorite platform and programming language.

• Multiversed. Don't give up to FSUIPC offsets or SimConnect variables.If you are familiarized with them, you can still use them in FlightVars thanksto its data multiverse support. You may access several universes of data asFSUIPC offsets or SimConnect variables and events. You can even access gaugeLVARs through FlightVars!

• Connectiveness. Don't limit your addon to the Windows IPC communicationor TCP connectivity. FlightVars supports several transport layers allowingyour addon to communicate with the simulator using different transports.Use your Arduino board through serial port over USB, connect your RaspberryPi using UDP, your Linux daemon using TCP, or your Windows addon using IPC.Just choose your platform and the appropriate channel, and let FlightVarsdo the rest.

• Open source. FlightVars is open. Open source, open culture, open mind.And, of course, it's for free.

Current limitations

What you read above is not fully true. These are the objectives of FlightVars.It's roadmap. But the road is quite long, and many many lines of code have to bewritten until all told above is fully implemented.

The basic architecture of FlightVars is aligned with the objectives discussedin the previous section. It's written in a really fast and secure programminglanguage (Rust). Under the hoods, a reactive model is used in combination withasynchronous IO to have the best performance. The architecture supports multipleuniverses of data (aka domains). But do not expect awesome functionalitiesas MQTT support in the early versions.

Having said that. The current version of FlightVars is 0.1. This is what itsupports right now:

• OACSP protocol v2 compatible with OACSP library for Arduino.
• Serial port communication.
• Access to FSUIPC offsets.
• Access to LVARs.

The rest of features mentioned in the introduction section are still underdevelopment.

Installing

FlightVars install process is pretty easy. You only have to download theinstallation program and follow the instructions.

Since FlightVars is open source software, you might want to build it from itssources. If so, please read the next section below.

Build instructions

FlightVars is written in Rust programming language. If you want to build fromsources you will need the Rust package for Windows GNU 32-bit installed inyour system.

Once installed, you can open a terminal with the appropriate settings withWindows Start menu -> All Programs -> Rust -> Rust 1.X Shell. A command promptwill open. Go to the directory where FlightVars source code was downloadedand type:

After building is finished, FlightVars plugin will be located intarget/release/flightvars.dll relative to the source code directory. You canplace the DLL in Modules/ subdirectory of your FSX/P3D installation andconfigure the DLL.xml file to load the plugin on simulation startup (check outthis article if you don't know what's this file for).