How do I set up and use SimConnect in Prepar3D?

Local SimConnect clients in Prepar3D usually need no manual setup: install the runtime required by the add-on, load a scenario, then start the client. Network clients require SimConnect.xml on the Prepar3D PC and SimConnect.cfg remotely. There is no global Options switch or bundled “SimConnect Manager”; add-ons may provide their own connection dialogue.

What does SimConnect do in Prepar3D, and is there a SimConnect Manager?

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

Prepar3D does not include a universal SimConnect Manager, connection panel or Options-menu switch. If an add-on tells you to open a connection manager, that manager belongs to the add-on and may appear as a separate program, tray utility or settings dialogue.

How do I set up SimConnect for a local P3D add-on?

A local external client normally connects automatically once Prepar3D has loaded a scenario.

1. Check the supported Prepar3D version. SimConnect retains useful backward compatibility, but that does not make every older application compatible with every P3D release.
2. Run the add-on’s normal installer. A properly packaged product should install or request its required SimConnect runtime.
3. Start Prepar3D and load a scenario. Wait until the aircraft is fully loaded before opening the client.
4. Start the external application. Select its Prepar3D, P3D or SimConnect connection option if it provides one.
5. Confirm live data in the client. Look for a connected status, the loaded aircraft, coordinates or changing flight data. Prepar3D itself has no general connection-status window.

Do not create SimConnect.xml or SimConnect.cfg merely to fix a local client. An obsolete network profile can make an application attempt a remote connection instead of using the normal local connection.

SimConnect.msi, SimConnect.dll downloads and “it is not there”

The safe source for SimConnect.msi is the redistributable directory supplied with Prepar3D or the add-on’s own installer. Under the actual simulator installation folder, look in:

<Prepar3D installation folder>\redist\Interface\...\SimConnect.msi

The intermediate folders identify different supported interfaces and can vary between Prepar3D releases. Install the package requested by the application rather than assuming the newest-looking one is correct. SimConnect interfaces can be installed side by side, so installing one legacy runtime does not necessarily replace another.

If you searched the main Prepar3D folder and thought “it is not there”, check the nested redist\Interface directories and confirm that you are looking at the real simulator installation, not its Documents or AppData folder. If the official redistributables are missing, repair the Prepar3D installation or rerun the add-on installer. Our SimConnect runtime installation guidance explains how to identify the appropriate supplied package.

Do not download a loose SimConnect.dll. A standalone DLL may have the wrong interface version or processor architecture and may omit the manifests and side-by-side components installed by the MSI package. Never copy an arbitrary SimConnect.dll into the Prepar3D directory or a Windows system folder.

These absences are often normal:

• SimConnect.xml is commonly absent until a network listener or particular add-on requires it.
• SimConnect.cfg is commonly absent for local use; it belongs to a client that needs explicit connection settings.
• SimConnect.msi is not normally placed beside Prepar3D.exe; it is stored below redist\Interface.
• A loose SimConnect.dll beside an external program is not a reliable test of whether the required runtime is installed.

Which Prepar3D version and architecture does the add-on need?

Compatibility depends on whether the add-on is an external client or a DLL loaded inside Prepar3D.

An external 32-bit application can communicate with a 64-bit simulator because it runs as a separate process. It needs a compatible client runtime, but its architecture does not have to match the Prepar3D process.

An in-process DLL is different: it is loaded directly into the simulator and must match its processor architecture and supported API generation. Prepar3D v4 and later are 64-bit, so they cannot load a 32-bit DLL. Installing another legacy SimConnect runtime will not convert an incompatible module.

Developers should install the SDK matching their target Prepar3D release and build against its libraries, headers or managed assemblies. Once connected, SimConnect applications read simulator variables and transmit events; our guide to Prepar3D SimVars and events covers that application-level work.

How do I configure SimConnect over a network?

Network SimConnect requires a server listener on the Prepar3D PC and matching connection details on the remote client PC. Use it only across a trusted local network.

Where does SimConnect.xml go?

The normal version-specific location is the Documents folder belonging to the Windows account that runs Prepar3D:

C:\Users\<Windows user>\Documents\Prepar3D vX Files\SimConnect.xml

Replace vX with the installed major version, such as the exact Prepar3D vX Files folder created by that release. Do not type vX literally. If Windows redirects Documents to OneDrive or another location, use the actual Documents folder shown in File Explorer.

This is normally not the %APPDATA%\Lockheed Martin\Prepar3D vX settings directory. Looking in the wrong user profile or the folder for another Prepar3D major version is one of the most common reasons the simulator appears to ignore the file.

What should SimConnect.xml contain?

A minimal IPv4 listener uses Protocol, Scope=global and an unused TCP Port. The following is valid as a complete new file; port 500 is only an example:

<?xml version="1.0" encoding="Windows-1252"?><SimBase.Document Type="SimConnect" version="1,0"><Descr>SimConnect</Descr><Filename>SimConnect.xml</Filename><Disabled>False</Disabled><SimConnect.Comm><Disabled>False</Disabled><Protocol>IPv4</Protocol><Scope>global</Scope><Port>500</Port></SimConnect.Comm></SimBase.Document>

Save it as plain text with the exact filename SimConnect.xml, not SimConnect.xml.txt. If a file already exists, back it up and add or edit the SimConnect.Comm block inside its existing SimBase.Document root. Do not paste a second XML declaration or overwrite communication blocks used by other add-ons.

The server example deliberately does not contain the PC’s LAN address. With a global IPv4 listener, the remote client supplies the address to contact.

What should the remote SimConnect.cfg contain?

On the client computer, create SimConnect.cfg in the location read by that application. For a simple external client this is commonly beside its executable, but packaged add-ons may use their own data folder or connection dialogue.

A minimal four-line configuration is:

[SimConnect]

Protocol=IPv4

Address=192.168.1.50

Port=500

Replace 192.168.1.50 with the Prepar3D computer’s private LAN address. Do not use 127.0.0.1 or localhost when Prepar3D is on another computer. The port must exactly match the value in SimConnect.xml.

How do I start and secure the network connection?

1. Give the Prepar3D PC a stable LAN address. A router DHCP reservation prevents the address changing after a restart.
2. Install the required runtime on the remote PC. The client may require a SimConnect redistributable even though Prepar3D itself is not installed there.
3. Add a private-network firewall rule on the Prepar3D PC. Allow Prepar3D.exe or the selected inbound TCP port on the Windows Private profile. If outbound connections are restricted on the client PC, allow the client application there as well.
4. Restart Prepar3D. Changes to SimConnect.xml are read when the simulator starts. Load a scenario fully before launching the remote client.
5. Keep the listener on the LAN. Do not configure router port forwarding, expose the port to the public internet or enable an unnecessarily broad Public-profile firewall rule.

Why will P3D SimConnect not connect, and can I fix it?

Most P3D SimConnect failures come from the wrong version folder, malformed XML, mismatched ports, misplaced client configuration or a firewall rule using the wrong network profile.

• Verify the Documents folder and major version. The file must be in the Documents location used by the same Windows account running Prepar3D and inside that release’s exact Prepar3D vX Files folder.
• Check the real filename. Enable file extensions in File Explorer and make sure the file is not named SimConnect.xml.txt or SimConnect.cfg.txt.
• Validate the XML structure. There must be one XML declaration, one SimBase.Document root and correctly nested closing tags. Replace curly quotation marks introduced by a word processor with ordinary text characters.
• Confirm the listener is enabled. Both relevant Disabled entries should be False, with Protocol set to IPv4 and Scope set to global.
• Match the port exactly. The server XML, remote CFG and firewall rule must all use the same unused TCP port.
• Check the remote address. The CFG must contain the Prepar3D PC’s present LAN address, not the client PC’s address and not a public internet address.
• Put SimConnect.cfg where the client reads it. If placing it beside the executable has no effect, use the add-on’s documented configuration folder or its own connection manager.
• Use the Windows Private network profile. A rule limited to Private networks will not apply if Windows has classified the LAN as Public. Correct the profile rather than permanently disabling the firewall.
• Install the requested client runtime. A missing-runtime or side-by-side error is separate from an XML or firewall problem.
• Restart after every server-file change. Editing SimConnect.xml while Prepar3D is running does not reliably reconfigure the active listener.

For a useful split test, start Prepar3D and load a scenario, then run Test-NetConnection 192.168.1.50 -Port 500 in PowerShell on the remote PC, substituting your address and port. If TcpTestSucceeded is false, concentrate on the server file, address and firewall. If it is true but the add-on still fails, check the CFG location, runtime and add-on compatibility.

SimConnect networking is not Prepar3D multiplayer. It transports simulator data and commands between Prepar3D and client software; it does not create a shared flying session.