How do I set up and use SimConnect in Prepar3D?

To set up SimConnect with Prepar3D, install the runtime required by your add-on, start Prepar3D, then launch the client application. Local clients normally need no configuration. For a second PC, enable a server connection in SimConnect.xml, point SimConnect.cfg to it, and allow the selected port through Windows Firewall.

What does SimConnect do in Prepar3D?

SimConnect is the application programming interface through which external utilities and compatible add-ons exchange data and commands with Prepar3D. Prepar3D acts as the server; flight planners, hardware interfaces, moving maps, instructor stations and custom applications act as clients.

There is no general SimConnect switch in Prepar3D's Options menu. A correctly installed local client normally connects automatically after the simulator has started and a scenario has loaded.

How do I install SimConnect for a local application?

1. Check the application's compatibility. Confirm that it supports your major Prepar3D version. SimConnect offers considerable backward compatibility, but that does not make every older add-on compatible with every Prepar3D release.
2. Use the application's installer first. A well-packaged add-on installs or requests the runtime it was built against. Do not copy an arbitrary SimConnect.dll into the simulator folder or a Windows system directory.
3. Install a required legacy runtime. If the application reports that SimConnect is missing, close Prepar3D and look under <Prepar3D installation folder>\redist\Interface\. Its labelled subfolders contain supported redistributable installers. Run only the SimConnect.msi package required by the application.
4. Start Prepar3D before the client. Load a scenario completely, then open the external application and select its Prepar3D or SimConnect connection option if it has one.
5. Confirm the connection in the client. Most applications show a connected status, active aircraft details or changing position data. Prepar3D itself does not display a universal SimConnect status panel.

A mistake we see constantly is installing only the newest available runtime. Legacy SimConnect interfaces are installed side by side rather than replacing one another, so an older client may specifically need the interface against which it was built.

Prepar3D v4 and later are 64-bit simulators. An external 32-bit application can still connect when it has its own compatible runtime, but an in-process 32-bit DLL cannot be loaded into a 64-bit Prepar3D process.

How do I configure SimConnect over a network?

A remote SimConnect connection requires matching server and client settings on a trusted local network. Avoid exposing its port to the public internet or configuring router port forwarding.

1. Give the Prepar3D PC a stable LAN address. A DHCP reservation is preferable to an address that may change after either computer restarts.
2. Configure the server file. On the Prepar3D computer, locate %APPDATA%\Lockheed Martin\Prepar3D vX\SimConnect.xml, where vX is the installed major version. Preserve any existing entries and add or enable a <SimConnect.Comm> block using the matching SDK or application's supplied template.
3. Set the listener values. The server entry normally uses Protocol set to IPv4, Scope set to global, Disabled set to False, the Prepar3D computer's LAN address and an unused port. XML must remain well formed.
4. Configure the remote client. Create or edit SimConnect.cfg in the location expected by the application—commonly beside its executable—or use its connection dialogue. Under [SimConnect], set Protocol=IPv4, Address to the Prepar3D computer's LAN address and Port to exactly the same number used in the server file.
5. Install the client runtime remotely. The second computer may still require the SimConnect redistributable even though Prepar3D is not installed there.
6. Allow the connection through the firewall. Permit Prepar3D and the configured port on private networks. Restart Prepar3D after changing SimConnect.xml, load a scenario, then start the remote client.

Do not replace a working SimConnect.xml merely to add another application. One server file can contain several communication blocks, and overwriting it may disconnect an existing weather engine, hardware bridge or instructor station.

What do developers need to use SimConnect?

Developers should install the SDK corresponding to the target Prepar3D release and build against its SimConnect interface. Our explanation of the matching Prepar3D SDK, libraries and sample workflow covers the installation side without confusing it with the end-user runtime.

A client opens a SimConnect connection, defines the simulator variables it needs, subscribes to events or requests data, and processes messages through its dispatch loop. The waypoint and AI-aircraft SimConnect example demonstrates those core techniques; its API concepts remain useful, but Prepar3D projects should use the appropriate Prepar3D SDK rather than copying old binaries into the simulator.

Why will SimConnect not connect?

• “SimConnect not found” or a side-by-side configuration error: install the exact legacy runtime requested by the application. Repairing the application may also restore its prerequisite installer.
• The local client times out: make sure Prepar3D has finished loading a scenario, then check that the application supports that Prepar3D generation and is not pointing to an obsolete network profile.
• Local access works but remote access fails: recheck the server address, port, Scope=global, firewall profile and location of SimConnect.cfg. The client address must not be 127.0.0.1 when Prepar3D runs on another computer.
• Prepar3D ignores the server file: verify that it is in the AppData folder for the correct Prepar3D version, is named exactly SimConnect.xml and contains valid XML. Restart the simulator after every server-file change.
• A DLL reports the wrong format or will not load: check processor architecture. An in-process module must match the simulator, whereas an external client runs as a separate process.
• The connection drops immediately: look for a duplicated port, security software blocking the process, an unstable LAN address or two applications rewriting the same configuration file.

Is SimConnect the same as Prepar3D multiplayer?

SimConnect networking is not multiplayer; it carries simulator data and commands between Prepar3D and client software. To fly with another person in a shared session, use the simulator's separate Prepar3D multiplayer configuration.