LINDA Support for MSFS 2020

[ScotFlieger 280]

Introduction

MSFS 2020 is a completely different beast than previous flight simulators like FSX and P3D. The interface for add-ons and accessories like LINDA has been reworked making it not an easy job to interface with. Thanks to the development of FSUIPC7 and the WASM module, LINDA is able to regain most of its original functionality. However, additional set up actions are required by users to ensure correct operation. Previous knowledge of setting up LINDA does not always apply and can be counter productive.

These notes are provided to guide LINDA users to gain a reliable installation.

Lvars, Hvars and Events

Previously, FSX/P3D made use of Lvars, Controls and Offsets that allowed LINDA to interface with the Flight Simulator via FSUIPC. These are still available but the use of Lvars has subtly changed with MSFS. In addition, FSUIPC7/WASM introduce Events in the form of Hvars and .EVT files. Events are used to trigger actions within the simulator (eg. pressing a button).

Lvars are not immediately released by MSFS to FSUIPC7 on start up. It is necessary to start MSFS and load the chosen aircraft ready to fly. The number of Lvars that can be read is limited to 3066 (in FSUIPC7 7.3.6). With some aircraft this number can be exceeded and cause problems with certain sophisticated aircraft (eg. Fenix A320). A LvarScanDelay= parameter is provided to delay the search for available Lvars (see below). When changing between different aircraft additional actions may be necessary to flush old Lvars.

Hvars are provided in .hvar files in the HvarFiles folder in /FSUIPC7. These have the prefix H:. The Hvars are matched to the loaded aircraft by string match based on the aircraft name (eg. FBW A32NX matches to A32NX FBW.Hvar).

Events are provided in .EVT files in /FSUIPC7. These files are indexed in FSUIPC7.INI and are referenced by the order and list of events. These files are installed with the LINDA aircraft module if required.

Lvar/Hvar Count

The number of Lvars/Hvars accessed by FSUIPC7/LINDA gives a good indication that everything should work correctly. The Lvars/Hvars count for each aircraft are:

• Fenix A320 should display around 1770 to 1870 Lvars and no Hvars.
• FBW A32NX should display around 1450 to 1500 Lvars and 220 Hvars.
• PMDG 737 should display 1800 to 1900 Lvars and no Hvars.

A problem with Lvars will display a Check Lvars message. Any value different from these or the warning will require that MSFS and FSUIPC7/LINDA be restarted (see below).

Installation Guidelines

The latest version of FSUIPC7 (currently 7.3.6) should be installed using the Install FSUIPC7 executable. It is installed in a /FSUIPC7 folder ideally in a root directory. You must have a full paid registered copy and remember to click Register button during installation. You also need to select the install WASM module option during installation. The WASM module is installed in the MSFS /Community fsuipc-lvar-module folder - the FSUIPC_WASM.ini file can be found in this folder (more later).

LINDA 4.1.x is installed into /FSUIPC7 by dragging and dropping the LINDA.EXE and other files/folders into /FSUIPC7.

There are a limited number of LINDA aircraft modules available for MSFS (FBW A32NX, Fenix A320 and PMDG 737). These should be installed using the LINDA Maintenance function as follows:

• Click Maintenance.
• Under Import Aircraft Module click Select Source Folder.
• Navigate to the downloaded module folder. This displays the module name and version.
• Click Install/Overwrite button.

Additional Settings

Some additional settings are need to get everything working.

Locate the MSFS /Community folder (C:\Users\[Your User Name]\AppData\Local\Packages\Microsoft.FlightSimulator_8wekyb3d8bbwe\LocalCache\Packages\ for MS Store installation). Open FSUIPC_LVAR_MODULE folder and edit FSUIPC_WASM.INI. Add these lines:

LvarUpdateFrequency=6Hz
RemoveLvarsWhenParked=No
UseAirLocForHvars=No
LvarScanDelay=60

Edit the FSUIPC7.INI file in /FSUIPC7 and add the following line to the [General] block:

UseAirLocForProfiles=Yes

and ensure that the [WAPI} block is added:

[WAPI]
EnableWAPI=Yes

Starting Everything

It is strongly recommended that you start MSFS, load the desired aircraft ready to fly and wait a minute before starting FSUIPC7 and LINDA.You should also click Restart LUA Engine as the last thing. Ensure that the correct aircraft appears in the top box outlined in orange.

When everything is running, you can check that the Lvars, Hvars and Events are loaded by selecting LINDA Tracer. The number of Lvars is displayed in top left corner (under Lua Variables). For Fenix A320 this should read around 2177/2177. The Hvars are listed under the Hvars tab (top right). Only the FBW A32NX uses Hvars and 220/220 should be listed. Each .EVT file is listed under the Events tab.

Changing Aircraft

Should you experience issues when changing aircraft I have found the following procedure resolves issues with the visibility of Lvars.

• Open MSFS and load new aircraft.
• Start FSUIPC7 and LINDA.
• In FSUIPC7 window click Add-ons / WASM / Reload.
• In FSUIPC7 window click Add-ons / WASM / List Lvars.
• Close and restart everything.

Performance

Experience with FSUIPC7 / WASM / LINDA has shown some impact on performance compared to previous versions. For example when a button is first pressed there can be a slight delay before that operation is passed to LINDA for action. Subsequent presses tend to be actioned more quickly. 

Reporting Issues and Problems

Should you experience problems please carefully read and follow the Fault Diagnosis Procedure (under LINDA Support). Then email the fsuipc7.log and linda2.log to me at linda @ awginfosys dot net. Include these configuration files if they relate to a problem with your joystick or VRI MCP setup: /linda-cfg/aircrafts/{your aircraft}/config-hid.lua and config-mcpX.lua renaming the extension to .txt.

Edited June 27, 2022 by ScotFlieger
Added Lvar count information

[ScotFlieger 280]

Added Lvars/Hvars count information.