DisplayCAL Not Detecting Your Colorimeter? 8 Fixes

DisplayCAL shows “no instrument detected” even though your colorimeter is plugged in. Before you assume the hardware is dead, work through these fixes. They come from real user reports, including GitHub issue #304, where an i1 Display Plus HL was invisible to the software.

Fix 1. Install the ArgyllCMS Instrument Drivers (Windows)

DisplayCAL needs Argyll’s USB driver, not the manufacturer’s. In DisplayCAL go to Tools, then Instrument, then Install ArgyllCMS instrument drivers. Alternatively, run ArgyllCMS_install_USB.exe as administrator from the Argyll_V3.5.0\usb folder. Then check Device Manager: your instrument should appear under Argyll libusb-win32 devices.

Fix 2. Use Zadig if the Install Fails

If the driver installation fails (often due to Windows driver signature enforcement), use Zadig to manually replace the instrument’s driver with libusb-win32. This is the standard fallback documented in our quickstart guide.

Fix 3. Plug Directly Into the Computer

The issue #304 reporter made a point of connecting directly to the computer’s USB port rather than through a USB-C docking station. Docks and hubs are a frequent source of detection failures. Also try a different cable and a different port.

Fix 4. Check ArgyllCMS.inf for Your Instrument (Advanced)

This is an advanced, user-reported fix from issue #304. Editing driver files can break driver installation. Back up the file first, and only try this if the standard install does not list your instrument.

In the issue, the Argyll USB driver package had the reporter’s instrument commented out in ArgyllCMS.inf:

;"Eye-One Display 3 (Argyll)" = LIBUSB0_DEV, USB\VID_0765&PID_5020

The reporter uncommented the three Eye-One Display 3 entries (32-bit and 64-bit sections), re-ran the installer, and both instruments appeared. If your instrument is a rebranded i1 Display Pro variant (Calibrite, NEC SpectraSensor, HP DreamColor), it may share the same VID/PID (0765:5020) and be affected the same way. Note: newer ArgyllCMS 3.5.0 driver packages may already include these entries, so upgrading ArgyllCMS is the safer first try.

Fix 5. One Instrument at a Time

Issue #304’s title mentions problems appearing after inserting a third instrument. If you have multiple meters connected, unplug all but one and test. VID/PID conflicts between similar devices are a known source of confusion.

Fix 6. Linux: Check USB Permissions

On Linux, your user must be able to access the USB device. Add yourself to the plugdev group and make sure the udev rules for the instrument are installed, then unplug and reconnect. See our Linux guide.

Fix 7. macOS: Check Permissions and the Cable

On macOS there is no driver to install. Detection failures are usually the cable, a hub, or (on newer macOS) a permission prompt you dismissed. See our macOS guide.

Fix 8. Confirm the Instrument Works Elsewhere

Test the colorimeter with the manufacturer’s own software (Calibrite Profiler, Spyder software). If it is not detected there either, the problem is hardware, cable, or USB, not DisplayCAL.

Still Not Working?

  • Run DisplayCAL’s instrument detection with logging and look for USB errors. Paste them into issue #304 or open a new issue.
  • Try our troubleshooting hub for related fixes.

Related: DisplayCAL troubleshooting hub | Quickstart guide | Fix “new_disprd failed” error

Frequently Asked Questions

Why does DisplayCAL see my colorimeter but ArgyllCMS tools do not (or vice versa)?
DisplayCAL talks to instruments through ArgyllCMS drivers. If the OS-level USB driver is the manufacturer’s instead of Argyll’s libusb driver, Argyll tools, and therefore DisplayCAL, cannot open the device. This is the most common cause.
Do I need to disable driver signature enforcement on Windows 11?
The reporter in issue #304 did disable it as a prerequisite for installing the Argyll USB driver. Whether you need it depends on your Windows configuration. Try the normal install first.
My instrument worked in DisplayCAL 3.8.9.3 but not in the py3 branch. Why?
In issue #304, the older version recognized the instruments while the newer Argyll USB driver package did not list them. The cause was commented-out entries in ArgyllCMS.inf. Newer ArgyllCMS versions (3.5.0) have updated driver packages, so upgrading may resolve it.
Can I use a USB hub or docking station?
Users report mixed results. The issue #304 reporter connected directly to the computer’s USB port rather than through a dock as a troubleshooting step. Direct connection is the safest test.