Setup guide · the SimConnect files

Setup says it did not find the SDK. Here is what to do.

ATC Relay needs two small free files from Microsoft. They come with Microsoft's SDK, a free kit for people who make add-ons for Microsoft Flight Simulator. You do not need to be a developer, and this guide assumes you have never installed an SDK.

I have not installed the SDKStart at step 1 and follow every step
I already installed itGo straight to giving ATC Relay the two files (step 4)
Setup said the folder was wrongRead the fixes at the end

The ATC Relay Setup finish screen with an amber message saying the Microsoft Flight Simulator SDK was not found, an unticked Start ATC Relay Host now box, and a Choose the SDK folder button — This is the screen you are on. It is normal: the two files come from Microsoft, so Setup asks you for them.

Why we do not include the files. The two files belong to Microsoft, and we may not hand them out. Get them only from Microsoft's own installer, using the steps below. Do not download SimConnect files from any other website.

Using Microsoft Flight Simulator 2020? It is experimental, and the steps below are the same: turn on Developer Mode, then Help, then SDK Installer, and the installer looks the same. The only difference is the folder name: the MSFS 2020 installer makes a folder called MSFS SDK, and the MSFS 2024 one makes MSFS 2024 SDK. Wherever this guide says MSFS 2024 SDK, use the folder your installer made. It still contains the SimConnect SDK folder.

1Check first: do you already have it?

You may already have the SDK from another add-on. Open File Explorer and look on your C: drive for a folder called MSFS 2024 SDK (MSFS SDK if you use MSFS 2020). You can also type C:\MSFS 2024 SDK into the address bar at the top of File Explorer and press Enter.

The folder is there: skip to step 4.
Setup already showed a green line saying the two SimConnect files were copied: you are done. Start ATC Relay Host.
No such folder: carry on with step 2. That is normal.

File Explorer showing the folder MSFS 2024 SDK with a folder called SimConnect SDK inside it — What the SDK folder looks like when it is installed. Inside it is a folder called **SimConnect SDK**.

2Turn on Developer Mode in Microsoft Flight Simulator 2024

Developer Mode adds a toolbar across the top of the simulator screen. The SDK installer is inside that toolbar.

Start Microsoft Flight Simulator 2024 and open its Options.
Choose General.
Find Developer Mode and switch it On.
A toolbar appears along the top of the screen. If you cannot see it, move the mouse to the top edge of the screen.

The simulator's General options page with the Developer Mode option visible and switched off — The Developer Mode option, still off.

The developer toolbar across the top of the simulator screen after Developer Mode was switched on — The toolbar that appears across the top once Developer Mode is on.

You can leave Developer Mode as it is once you are done.

3Install Microsoft's SDK

In the top toolbar choose Help, then SDK Installer.
Your web browser opens and downloads an installer file whose name ends in .msi.
Open that file from your browser's download list. You may see a Windows permission prompt: it is Microsoft's own installer, so choose Yes.
Click through the installer and keep the folder it suggests. Normally that is C:\MSFS 2024 SDK (C:\MSFS SDK for MSFS 2020). Wait until it says it has finished.

This is Microsoft's own installer, from the simulator's own menu. Always take the SDK from there, so it matches the simulator you have installed. If a simulator update ever stops ATC Relay connecting, repeat this step.

The Help menu open in the developer toolbar with SDK Installer highlighted — Help, then SDK Installer.

A web browser showing the SDK installer file with the .msi ending finishing its download — Your browser downloads a file ending in .msi.

The SDK installer's folder page showing the default folder C:\MSFS 2024 SDK — Keep the folder the installer suggests.

Microsoft's own instructions, if you want to read them: SDK Overview, Developer Mode.

4Give ATC Relay the two files

There are two ways. The first is the easy one.

A. Let Setup do it (recommended)

Run the ATC Relay Setup again. Or, on Setup's finish screen, press Choose the SDK folder....
Pick the folder named MSFS 2024 SDK (MSFS SDK for MSFS 2020). It is the one that contains a folder called SimConnect SDK. Then press OK.
You should see a green line: The two SimConnect files were copied from your MSFS SDK.

If you installed the SDK somewhere else, pick that folder instead. The rule is the same: choose the folder that contains SimConnect SDK.

Setup's folder picker with the MSFS 2024 SDK folder selected — Pick the folder that contains SimConnect SDK.

Setup's finish screen with the green message that the two SimConnect files were copied — The green line means it worked.

B. Copy them yourself

You need two files from inside the SDK folder. Their full paths (if your SDK is on C:) are the ones below; for MSFS 2020 use MSFS SDK in place of MSFS 2024 SDK:

C:\MSFS 2024 SDK\SimConnect SDK\lib\SimConnect.dll

C:\MSFS 2024 SDK\SimConnect SDK\lib\managed\Microsoft.FlightSimulator.SimConnect.dll

Copy both into this folder, which is where ATC Relay lives:

%LOCALAPPDATA%\Programs\ATC Relay\Service

To open that folder without hunting for hidden folders: press the Windows key and R together, paste the path above (Ctrl and V) and press Enter. Then drag or paste the two files into the window that opens.

The SimConnect SDK lib folder in File Explorer showing SimConnect.dll — File one: SimConnect.dll, in the **lib** folder.

The managed folder inside lib showing Microsoft.FlightSimulator.SimConnect.dll — File two: Microsoft.FlightSimulator.SimConnect.dll, in the **managed** folder inside lib.

The ATC Relay Service folder with both SimConnect files in place — Both files in the Service folder.

5Check it worked

Start ATC Relay Host. Its start-up checklist should go green. That checklist proves the app can reach the simulator through the two files. If it stops with a message that something did not answer, one of the files is missing or in the wrong place: go to the fixes below.

The ATC Relay Host start-up checklist with every line green — An all-green checklist.

?If it did not work

What you see	What to do
"Both SimConnect files were not found under that folder"	You picked a folder inside or above the SDK. Pick the one that contains SimConnect SDK (normally C:\MSFS 2024 SDK, or C:\MSFS SDK for MSFS 2020).
There is no Developer Mode option	Update the simulator and look again in Options, General. Microsoft describes it on its Developer Mode page. If it is still missing, email us with a photo of that options page.
The SDK Installer does nothing, or nothing downloads	Check your browser did not block the download. Then open Microsoft's SDK Overview page and follow it from there.
I installed the SDK on another drive or in another folder	Use way A in step 4 and pick that folder.
Setup said "copied" but the checklist still stops	Check that both files are in the Service folder (way B, last picture). If they are, email us `Service\service_stdout.log`.
A blue box says "Windows protected your PC" when running our installer	Choose More info, then Run anyway. Do this only for a file that came directly from Navisphere Studios.

Still stuck? Email support@navispherestudios.com with a photo of the screen and, if you can, the file Service\service_stdout.log. We will help.