Install QModMaster on Ubuntu/Debian (Build from Source)

QModMaster runs fine on Linux — it is written in Qt, after all — but there is no official .deb package, no PPA, and no Flatpak. On Ubuntu and Debian you install it by compiling the source yourself. The whole process takes about ten minutes once the dependencies are in place, and this guide walks you through every step: dependencies, source code, the qmake && make build, and the one serial-port permission gotcha that trips up almost everyone.

Why There Is No .deb Package

The upstream QModMaster project publishes only two things: a portable Windows .zip and the source code (via SourceForge). The project never shipped Linux binaries or distribution packages, so any .deb you find elsewhere is either unofficial or outdated. Building from source also guarantees you get the current stable release — v0.5.2 — rather than whatever happens to sit in a third-party repo.

Step 1: Install the Build Dependencies

Open a terminal and install the compiler toolchain plus the Qt 5 development packages QModMaster needs (notably QtSerialPort, which is not part of the default Qt install):

sudo apt update
sudo apt install build-essential qtbase5-dev qt5-qmake libqt5serialport5-dev git

Package names may vary slightly by distro version — on older releases the meta-package may be called qt5-default, and on Debian derivatives the same names above generally apply. If apt reports that a package has no installation candidate, search for it with apt search qt5 and pick the matching development package.

Step 2: Get the Source Code

Download the stable source archive from the official SourceForge files page — the file you want is qModMaster-code-0.5.2-3.zip:

mkdir -p ~/src && cd ~/src
wget https://sourceforge.net/projects/qmodmaster/files/qmodmaster/qModMaster-code-0.5.2-3.zip/download -O qmodmaster-src.zip
unzip qmodmaster-src.zip
cd qmodmaster

Alternatively, grab the code with Git if you prefer to track upstream changes:

git clone https://git.code.sf.net/p/qmodmaster/code qmodmaster
cd qmodmaster

Step 3: Build with qmake and make

QModMaster is a classic Qt .pro project, so the build is the standard two-command sequence:

qmake qmodmaster.pro
make -j$(nproc)

The -j$(nproc) flag just uses all your CPU cores to speed up compilation. When make finishes without errors you will find a fresh qmodmaster binary in the build directory.

Step 4: Run QModMaster

./qmodmaster

The main window should open and show the Modbus request grid and the Bus Monitor. For a quick smoke test, switch the interface to Modbus TCP, point it at a test device (or a local Modbus slave simulator), and try reading holding registers with function code 03. If you plan to use it regularly, create a desktop shortcut or a .desktop launcher pointing at the binary.

Step 5: Fix Serial Port Permissions (RTU Users)

If you use Modbus RTU over a USB-to-RS485 adapter, Linux will normally deny QModMaster access to /dev/ttyUSB0 with a permission error. The fix is to add your user to the dialout group:

sudo usermod -aG dialout $USER

Log out and back in (or reboot) for the group change to take effect, then confirm with groups. After that, the serial port appears in QModMaster’s port drop-down without needing sudo — do not run QModMaster as root, it is unnecessary and bad practice.

Common Build Errors and Fixes

“Project ERROR: Unknown module(s) in QT: serialport” — the QtSerialPort development files are missing. Install libqt5serialport5-dev and re-run qmake.

“qmake: command not found” — the Qt build tools are not installed or not on your PATH. Install qt5-qmake (and qtbase5-dev), then open a fresh terminal.

“cannot find -lGL” during linking — a common Qt build issue when the OpenGL development files are missing. Install libgl1-mesa-dev and run make again. These are generic Qt build problems, not QModMaster bugs, and the fixes above cover the vast majority of cases.

Need an adapter for Modbus RTU? QModMaster talks RTU through a USB-to-RS485 adapter — see our USB-to-RS485 adapter recommendations before you buy, or read the full buying guide.

Frequently Asked Questions

Is QModMaster available for Linux?

Yes, but only as source code — there is no official .deb, RPM, or Flatpak. Compile it yourself with qmake && make following the steps above and you get the full stable release (v0.5.2) with RTU, TCP, Bus Monitor, and all supported function codes.

Which Qt version does QModMaster need to build?

QModMaster is a Qt 5 project, so install the Qt 5 development packages (qtbase5-dev, qt5-qmake, libqt5serialport5-dev). Package names may vary slightly by distro version; if you only have Qt 6 available, expect build issues, since the project predates Qt 6.

Why does QModMaster report “permission denied” on /dev/ttyUSB0?

Your user is not in the dialout group, which owns serial devices on Ubuntu/Debian. Run sudo usermod -aG dialout $USER, log out and back in, and the port will open without root privileges.

Can I build QModMaster on Fedora, Arch, or other distros?

The same source code builds on any distro with Qt 5 — only the dependency package names change (for example qt5-qtbase-devel and qt5-qtserialport-devel on Fedora-style systems). The qmake && make steps and the dialout-group permission fix apply everywhere.

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