mrlm-net/simconnect

Go wrapper for SimConnect.dll — build Microsoft Flight Simulator 2020/2024 add-ons with type-safe, zero-dependency Go code.

Features

Engine — Direct SimConnect Access

• Full SimConnect DLL binding via syscalls — zero CGo, Windows-only
• Typed message stream via Go channels with callback handlers
• Manual and pre-built dataset definitions across 6 domains (aircraft, environment, facilities, objects, simulator, traffic)
• AI traffic management — create, remove, and control parked, enroute, and non-ATC aircraft with livery selection
• Facility data queries — airports, runways, parking, frequencies, VOR, NDB, waypoints, jetways, helipads, and 14 facility types total
• SimConnect.dll auto-detection via environment variables, SDK paths, and common installation locations

Manager — Production Lifecycle

• Automatic connection lifecycle with reconnection and health monitoring
• 60+ SimVar state tracking via SimState — camera, position, speed, weather, VR, environment, realism settings
• Channel-based and callback-based subscriptions with message type filtering
• 12 typed system event handlers — Pause, Sim, Crashed, CrashReset, Sound, View, FlightLoaded, AircraftLoaded, FlightPlanActivated, FlightPlanDeactivated, ObjectAdded, ObjectRemoved

Utilities

• Great-circle distance (haversine), altitude/distance/speed conversions, ICAO validation, WGS84 coordinate offsets
• Tiered buffer pooling and pre-allocated handler buffers for zero-allocation dispatching

Zero external dependencies — standard library only.

Quick Start

package main

import (
    "github.com/mrlm-net/simconnect"
)

func main() {
    client := simconnect.NewClient("MyApp", simconnect.ClientWithHeartbeat(simconnect.HEARTBEAT_6HZ))
    if err := client.Connect(); err != nil {
        panic(err)
    }
    defer client.Disconnect()
    // … interact with the simulator
}

Examples

All examples include standalone main packages with individual READMEs. Browse the examples folder or run any example directly:

go run ./examples/<name>

• Getting Started — basic-connection, await-connection, lifecycle-connection
• Manager Interface — simconnect-manager, simconnect-subscribe, simconnect-state, simconnect-events
• Data Operations — read-messages, read-objects, set-variables, emit-events, subscribe-events, using-datasets
• Facilities & Navigation — subscribe-facilities, read-facility, read-facilities, read-waypoints, all-facilities, airport-details, locate-airport, simconnect-facilities
• AI Traffic — ai-traffic, manage-traffic, monitor-traffic, simconnect-traffic
• Performance — simconnect-benchmark

CLI Tools

simvar-cli

simvar-cli is a Windows command-line tool for reading, writing, and streaming MSFS SimVars directly from a terminal. It connects to a running simulator via SimConnect and supports JSON, CSV, and table output formats.

# Build from source
cd cmd/simvar-cli
go build -o simvar-cli.exe .

# Read a SimVar
simvar-cli get "PLANE ALTITUDE" feet float64

# Stream continuously as NDJSON
simvar-cli --format json watch "PLANE ALTITUDE" feet float64

# Interactive REPL
simvar-cli repl

See cmd/simvar-cli for the full README and docs/simvar-cli.md for the complete reference.

Documentation

simconnect.mrlm.net — Full documentation website with getting started guide, configuration reference, and usage guides.

• Client Configuration — Engine/Client functional options
• Client API Reference — Complete Engine/Client API
• Manager Configuration — Manager functional options
• Manager Usage — Lifecycle management, subscriptions, state handling
• Request ID Management — ID allocation strategy and conflict prevention
• Event Lifecycle — Event lifecycle reference

Packages

• simconnect — Main entry point — New() for managed connection, NewClient() for direct engine access
• pkg/engine — High-level client, session lifecycle, message dispatching
• pkg/manager — Connection manager with auto-reconnect and state tracking
• pkg/types — Typed data structures, enums, events
• pkg/datasets — Pre-built dataset definitions (aircraft, environment, facilities, objects, simulator, traffic)
• pkg/convert — Unit conversions, ICAO validation, WGS84 coordinate offsets
• pkg/calc — Calculation helpers (haversine great-circle distance)
• pkg/registry — Cross-platform typed SimVar metadata catalogue (104 entries, no build tags)
• cmd/simvar-cli — Interactive CLI tool for reading, writing, and streaming SimVars

Installation

go get github.com/mrlm-net/simconnect

Requirements

Requirement	Version
Go	1.25+
Operating system	Windows
Microsoft Flight Simulator	2020 / 2024
SimConnect SDK	Bundled with MSFS

Contributing

Contributions are welcomed and must follow the Code of Conduct and common Contribution guidelines.

If you'd like to report a security issue please follow the security guidelines.

Sponsoring

This library is developed and maintained in personal time. Sponsorship helps cover the direct costs of keeping it accurate and active:

• MSFS 2024 license — required to test against the current simulator version
• Windows development environment — the only supported platform; ongoing hardware and OS costs
• Documentation hosting — simconnect.mrlm.net is served from a paid static hosting account
• Development time — research against undocumented SimConnect behaviors, writing typed wrappers, and reviewing contributions

If this library has saved you time, a one-time or recurring contribution via Revolut is appreciated. There is no obligation.

License

This project is licensed under the terms specified in the LICENSE file.

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^{_{All rights reserved © Martin Hrášek <@mrlm-xyz> and WANTED.solutions s.r.o. <@wanted-solutions>}}