FrSky Multiprotocol Module Setup Guide for ETHOS

This guide explains how to install the FrSky ETHOS Lua script for a Multiprotocol Module, how to update the module firmware, and how to confirm everything is working correctly. A lot of users do not realize the Lua script on the radio and the firmware inside the module are two different things. Both matter.

What This Guide Covers
• What Lua scripts are in ETHOS
• Where FrSky stores ETHOS files on GitHub
• Where to install the MULTI Lua script on the radio
• How to download the correct Multiprotocol firmware
• How to copy the firmware file to the radio and flash the external module
• How to confirm the Lua script and module firmware are working

What Is a Lua Script in ETHOS?

A Lua script in FrSky ETHOS is basically like a small app or plugin for the radio. It adds extra functions, menus, or device support that ETHOS can load from the SD card.

For a Multiprotocol Module, the Lua script allows ETHOS to properly recognize and work with the module. Without the correct script in the correct location, module support may not appear properly in the radio.

Simple way to think about it:
The Lua script is like an app on your phone.
The module firmware is the operating code inside the module itself.
They are not the same thing.

What Is GitHub and Why Does FrSky Use It?

GitHub is an online platform used to store and manage files, code, updates, documentation, and revision history. FrSky uses GitHub to host much of its ETHOS-related community content, including Lua files, issue tracking, updates, and other development resources.

For ETHOS users, this means some product support files are not only found in a traditional downloads page. In many cases, they are stored in FrSky’s public GitHub repositories.

FrSky ETHOS Community Repository
https://github.com/FrSkyRC/ETHOS-Feedback-Community

Where the FrSky MULTI Lua Script Is Located

The ETHOS Lua script for the Multiprotocol Module is located in FrSky’s ETHOS GitHub repository here:

The key file is:

main.lua

Where to Install the Lua Script on the Radio

On the radio SD card, the MULTI script should be installed in this exact path:

/scripts/multi/main.lua

That means:

  • The folder should be named multi
  • The file should be named main.lua
  • The file should be inside the /scripts folder on the SD card
Important:
Do not rename the file and do not move it to some random folder path. ETHOS expects the script in the proper location. If you rename it or put it elsewhere, module support may not load correctly.

What the Multiprotocol Module Actually Is

A Multiprotocol Module, often shortened to MPM or MULTI, is an external RF module that supports many different receiver protocols from multiple brands. This is what allows one radio to bind to a wide range of models that do not all use the same RF protocol.

The Multiprotocol project itself is an open-source project. The FrSky-branded or compatible modules still rely on MULTI project firmware, not some completely separate FrSky-only firmware ecosystem.

Downloading the Correct Multiprotocol Firmware

The module firmware is downloaded separately from the ETHOS Lua script.

For the FrSky-style IRX4 Lite / STM32-based module commonly used by North American ETHOS users, the typical filter settings are:

  • Firmware Version: latest stable
  • Module Type: STM32 4-in-1
  • Radio Type: Serial
  • Firmware Type: Air
  • Channel Order: AETR
North America Note
For most users in the United States and Canada using FrSky ETHOS radios with an IRX4 Lite style module, the common setup is the AETR / Air / Serial / STM32 combination shown above.

Example firmware filename:

mm-stm-serial-aetr-air-v1.3.4.31.bin

Important Warning About the Download Page Lua Files

The MULTI download page may also show Lua-related files such as:

  • Multi.txt
  • MultiLuaScripts.zip
Do not use those Lua files for FrSky ETHOS radios.
Those Lua files are intended for OpenTX / EdgeTX workflows, not the FrSky ETHOS Lua path used in this guide.

For ETHOS radios, use the FrSky ETHOS MULTI Lua script from GitHub and the module firmware .bin file from the MULTI project download page. They are separate parts of the setup.

How to Transfer the Firmware File to the Radio and Flash the Module

Once you have the correct .bin firmware file downloaded, you need to copy it to the radio and then flash the external module from ETHOS.

Step 1 — Connect the Radio by USB

Power on the radio and connect it to your computer using a USB cable.

The radio will present a USB mode selection screen. Choose:

ETHOS Suite

Do not select Joystick mode. ETHOS Suite mode is the one that allows the radio to mount as USB storage drives so you can copy files.

Tip:
If the radio does not show up on your computer as drives, disconnect it and reconnect it, then make sure ETHOS Suite is selected.

Step 2 — Open the Radio Drives

After selecting ETHOS Suite mode, the radio will appear as logical USB drives on your computer. One of these will be the radio SD card.

Open the SD card drive and locate the firmware folder:

/FIRMWARE

If the folder does not already exist, create it.

Step 3 — Copy the Firmware File

Copy the downloaded firmware file into the /FIRMWARE folder on the SD card.

/FIRMWARE/mm-stm-serial-aetr-air-v1.3.4.31.bin

Step 4 — Safely Disconnect the Radio

Eject the radio drives from your computer, then unplug the USB cable.

Step 5 — Flash the External Module

On the radio, open the file browser or file manager and navigate to the firmware folder. Highlight the firmware file, then long press on it to open the action menu.

Choose:

Flash External Device

The radio will then flash the firmware to the Multiprotocol Module installed in the external module bay.

Do not power off the radio during the flashing process.
Make sure the external module is fully installed in the radio before attempting to flash it.

How to Confirm the MULTI Lua Script Is Installed Correctly

After copying the MULTI Lua script to:

/scripts/multi/main.lua

ETHOS should automatically load the script during startup. You can confirm the script is working by checking if MULTI / MPM protocol options appear in the model settings.

How to Check

  1. Open your Model Setup page
  2. Scroll down to the External RF section
Model → External RF

When the script is installed correctly, you should see MULTI / MPM protocol options available.

Typical protocol options may include:

  • DSM2
  • DSMX
  • FlySky
  • Futaba SFHSS
  • Hubsan
  • V761
  • and many others
What this means
If you can select MULTI and see protocol choices, the Lua script is installed correctly and ETHOS is recognizing the module support.
If MULTI does not appear:
Check that the file exists at /scripts/multi/main.lua, that the folder name is multi, that the file name is main.lua, and that the radio was rebooted after copying the file.

How to Check the Multiprotocol Module Firmware Version

After flashing the module firmware, you can check the version directly from the radio.

How to Check

  1. Open Model Setup
  2. Scroll to External RF
  3. Set the external module type to MULTI
Model → External RF → MULTI

When the module initializes, ETHOS will query the module. The firmware version should appear in the module information area.

Example display:

MULTI v1.3.4.31

Depending on the ETHOS version, the firmware version may appear in the External RF info line or another module information area after MULTI is selected.

If no version appears:
Make sure the module is fully seated in the external bay, make sure External RF is set to MULTI, and re-check that the firmware flash completed correctly.

Final Verification Checklist

  • MULTI Lua script installed at /scripts/multi/main.lua
  • MULTI / MPM protocol options visible under Model → External RF
  • Multiprotocol firmware successfully flashed
  • Firmware version visible on the radio
Next Step: Flying Spektrum DSM2 / DSMX Models?
Many pilots install a Multiprotocol Module specifically to fly Spektrum aircraft.

Once the module is working, the next recommended tool is DSM Tools Suite for ETHOS.

View DSM Tools Suite Installation Guide →

Quick Summary

  • The ETHOS Lua script and the module firmware are two separate things
  • The FrSky ETHOS MULTI script should be installed as /scripts/multi/main.lua
  • The Multiprotocol firmware .bin file is downloaded separately from the MULTI project website
  • For ETHOS radio USB access, select ETHOS Suite mode
  • Copy the MULTI firmware file to /FIRMWARE on the radio SD card
  • Use the radio’s file browser and select Flash External Device to update the module
  • You can confirm the MULTI Lua script is working by checking for MULTI / MPM protocol options under Model → External RF
  • You can check the module firmware version by selecting MULTI under External RF and reading the version shown by ETHOS

Copyright © 2026 New England RC LLC. All rights reserved.
This guide is provided for educational and informational purposes only for customers and hobbyists using FrSky ETHOS radios, multiprotocol modules, and related RC equipment.

This content may not be copied, republished, redistributed, or reproduced in whole or in part without written permission from New England RC LLC.

FrSky, Spektrum, DSM2, DSMX, ETHOS, and other product names are trademarks of their respective owners and are used only for compatibility and identification purposes.