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Spectrum Scope FT 710
The Yaesu FT-710 can stream its live spectrum waterfall to RigControl Web over USB. This requires installing a small driver library (libft4222) from FTDI on your computer, and enabling the feature in the radio's settings.
This guide covers Linux (Fedora/RHEL and Debian/Ubuntu), macOS, and Windows.
Your FT-710 uses a single USB cable. When connected, your computer sees three separate USB devices exposed by that one cable:
| Device | Purpose |
|---|---|
| CP2105 (Silicon Labs) | CAT control serial port — used by rigctld |
| FT4222H (FTDI) | Spectrum scope data stream |
| USB Audio | Radio audio over USB |
You do not need a second cable for the spectrum scope.
The spectrum USB output is off by default. Turn it on through the FT-710's menu:
- Press the FUNC knob to open the menu.
- Rotate or touch to OPERATION SETTING, then press FUNC to enter it.
- Navigate to GENERAL.
- Find SCU-LAN10 and set it to ON.
- Press FUNC (or wait about 3 seconds) to save the setting.
- Touch BACK to return to normal operation.
With the radio connected and powered on, open a terminal and run:
lsusb | grep -i "0403:601c"Expected output:
Bus 001 Device 003: ID 0403:601c Future Technology Devices International, Ltd FT4222H
If nothing appears, check that the USB cable is fully seated and that SCU-LAN10 is enabled in the radio (see above).
FTDI does not publish libft4222 through any Linux package manager — you must download it directly from FTDI.
Go to the FT4222H Software Examples page and download the Linux package. Then extract it:
cd ~/Downloads
tar -xzf libft4222-linux-*.tgz
cd libft4222-linux-*Run the included installation script:
sudo ./install4222.shThis copies the library to /usr/local/lib/ and updates the linker cache.
If the script fails, install manually:
sudo cp build-x86_64/libft4222.so.1.4.4.170 /usr/local/lib/
sudo ln -sf /usr/local/lib/libft4222.so.1.4.4.170 /usr/local/lib/libft4222.so.1
sudo ln -sf /usr/local/lib/libft4222.so.1 /usr/local/lib/libft4222.so
sudo ldconfigldconfig -p | grep libft4222You should see at least one line referencing libft4222.so.1.
If you see nothing, /usr/local/lib may not be in the linker's search path — this is common on Debian and Ubuntu. Fix it:
echo "/usr/local/lib" | sudo tee /etc/ld.so.conf.d/local.conf
sudo ldconfigThen re-run ldconfig -p | grep libft4222 to confirm.
Fedora / RHEL: If you still get a "not found" error at runtime, also copy the file to
/usr/local/lib64/and re-runsudo ldconfig.
Fedora and RHEL run SELinux enforcing by default. Apply the correct file context so the library can be loaded:
sudo restorecon /usr/local/lib/libft4222.so*Verify the context is lib_t:
ls -lZ /usr/local/lib/libft4222.so*
# Expected: system_u:object_r:lib_t:s0If restorecon does not fix it (context shows unlabeled_t):
sudo semanage fcontext -a -t lib_t '/usr/local/lib/libft4222\.so.*'
sudo restorecon /usr/local/lib/libft4222.so*Debian / Ubuntu: SELinux is not used on these distributions — skip this step entirely.
Without this step, RigControl Web would need to run as root to read from the FT4222H. Create a udev rule to grant access automatically:
sudo tee /etc/udev/rules.d/50-ftdi-ft4222.rules > /dev/null << 'EOF'
# FTDI FT4222H (Yaesu FT-710 spectrum scope)
SUBSYSTEM=="usb", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="601c", MODE="0660", GROUP="dialout", TAG+="uaccess"
EOFThis rule grants access two ways: TAG+="uaccess" covers users logged into the local graphical desktop (seat0), and GROUP="dialout" covers everyone else — including remote-desktop/RDP sessions, which systemd-logind does not treat as seat sessions and therefore does not grant uaccess ACLs to. Make sure your user is in the dialout group (the same group used for the radio's CAT serial port):
sudo usermod -aG dialout $USER(Log out and back in for the new group membership to take effect.)
Apply the rule:
sudo udevadm control --reload-rules
sudo udevadm triggerUnplug and reconnect the USB cable so the rule takes effect on the device.
Remote desktop / headless setups: If you connect to this machine via a remote desktop session (e.g. GNOME Remote Desktop/RDP, VNC, X11 forwarding),
uaccessalone is not enough — onlyGROUP="dialout"will grant your session access. If the scope still reportsdevice not found (status 2)after confirming the device is connected and the library is installed, checkgetfacl /dev/bus/usb/<bus>/<device>(fromlsusb) and confirm your user is indialout(groups).
With the radio connected and powered on, open Terminal and run:
system_profiler SPUSBDataType | grep -A5 "FT4222"You should see an entry for the FT4222H. If nothing appears, check the USB connection and confirm SCU-LAN10 is enabled in the radio (see above).
Go to the FT4222H Software Examples page and download the macOS package.
Extract the archive and install the library:
sudo cp libft4222.1.dylib /usr/local/lib/
sudo ln -sf /usr/local/lib/libft4222.1.dylib /usr/local/lib/libft4222.dylibVerify the files are in place:
ls -l /usr/local/lib/libft4222*macOS marks files downloaded from the internet as quarantined. Remove the flag so the library can be loaded:
sudo xattr -d com.apple.quarantine /usr/local/lib/libft4222.1.dylibNo further configuration is needed for USB device access on macOS. If the app still cannot open the device, check System Settings → Privacy & Security for anything blocking USB access.
With the radio connected and powered on, open Device Manager (right-click the Start button → Device Manager).
Look for two FT4222H entries. They will typically appear under Universal Serial Bus controllers with the stock FTDI driver. You should see both Interface 0 and Interface 1 listed.
If they do not appear, check the USB connection and confirm SCU-LAN10 is enabled in the radio (see above).
The CP2105 CAT serial port will appear separately under Ports (COM & LPT) — this is expected.
RigControl Web communicates with the FT4222H through FTDI's D2XX API, which requires the stock FTDI driver that Windows installs automatically. Do not replace this driver with WinUSB, libusb, or any other third-party driver — doing so will prevent the spectrum scope from working.
To verify the correct driver is loaded:
- In Device Manager, right-click one of the FT4222H entries and choose Properties.
- Go to the Driver tab.
- The Driver Provider should be FTDI. If it shows libusb-win32, WinUSB, or anything else, the driver has been replaced and needs to be restored (see below).
If the driver was replaced (e.g. by a third-party tool):
- In Device Manager, right-click the FT4222H device → Uninstall device.
- Check Attempt to remove the driver and click Uninstall.
- Repeat for the second FT4222H interface.
- Unplug the FT-710's USB cable, wait a few seconds, and plug it back in.
- Windows will automatically reinstall the stock FTDI driver.
Go to the FT4222H Software Examples page and download the Windows package. It contains two DLL files that RigControl Web needs at runtime:
ftd2xx.dllLibFT4222-64.dll
Copy both files to %APPDATA%\RigControl Web\ (this is the same folder where RigControl Web stores its settings). To open this folder quickly, press Win+R, paste the following, and press Enter:
"%APPDATA%\RigControl Web"
If the RigControl Web folder does not exist yet, create it first.
Upgrading from a previous version? If you previously placed the DLLs in the program directory (e.g.
C:\Program Files\RIGCONTROL WEB\), the installer will automatically copy them to%APPDATA%\RigControl Webduring the upgrade — no manual action required.
RigControl Web will show a clear error on startup if either file is missing.
Once the library is installed:
- Open the Spectrum Scope panel settings (gear icon in the panel header).
- Under Spectrum Source, select FT-710 via USB.
- Turn on Enable Spectrum Scope.
- The Reader running indicator turns green when the app has successfully connected to the device.
The waterfall should appear within a second or two. If it does not, check the error message next to the status indicator.
Check the error message shown in the Spectrum Scope settings panel.
| Error | Most likely cause | Fix |
|---|---|---|
libft4222 not found |
Library not installed or not on search path | Redo the install steps for your platform; on Windows, ensure the DLLs are in %APPDATA%\RigControl Web
|
No FT4222 device found |
Radio not connected, or SCU-LAN10 not enabled | Check USB cable and radio menu |
device not found + using the FTDI D2XX driver (Windows) |
The FT4222H driver was replaced with WinUSB or libusb | Restore the stock FTDI driver — see Windows Step 2 |
LIBUSB_ERROR_ACCESS / permission denied (Linux) |
udev rule missing or not applied | Redo Linux Step 6 and replug the USB cable |
device not found (status 2) despite lsusb showing the device (Linux) |
Permission denied on the device node — common over remote desktop/RDP sessions, where uaccess ACLs are not granted |
Redo Linux Step 6 with GROUP="dialout", confirm your user is in dialout (groups), then replug the USB cable |
device not found on macOS |
USB access blocked by macOS security | Check System Settings → Privacy & Security for blocked USB access; also verify the quarantine flag was removed (macOS Step 3) |
libft4222 not found on macOS |
Quarantine flag still set | Run the xattr -d command from macOS Step 3 |
Start RigControl Web with --debug-spectrum for a detailed trace of the spectrum reader's activity:
From the command line:
./RigControl-Web-<version>.AppImage --debug-spectrumIn development:
npm run dev -- --debug-spectrumOutput appears in the terminal where you launched the app.
FTDI does not publish libft4222 to any Linux distribution's package repositories (DNF, APT, AUR, etc.) as of mid-2026. It must always be installed manually from FTDI's website as described above.