USB Driver v4.4 Installation Instructions

 Download driver v4.4  

System Requirements

Windows Vista or 7 (64-bit)?

Administrative privileges on your computer (please consult your system administrator for details)

Intel Core i3/i5/i7 processor...


Important Note If your computer is running 32-bit Windows?, we recommend that you install version 4.16 instead.


Driver version 4.4 is intended for use on computers which:


Computer processors reported as unreliable with USB driver 6.x


We have signed and posted legacy driver 4.4 as an interim measure. The driver provider (a third party) is aware of the unreliable communication issue and is currently working to resolve it.


The communication problem appears to affect all recent computers with Intel Core i3/i5/i7 processors whose motherboards lack an onboard USB 1.x controller and instead include a USB 2.0 rate-matching hub. If you cannot find a "Universal" or "Open" host controller in Device Manager under the "Universal Serial Bus" category, you may be better off "beta testing" v4.4 rather than waiting for v6.0 to fail.


Step by Step: Driver Installation

  1. Download and run (double-click) the file "" from the link above. Right-click the file and select "Extract All" to extract the driver files.


    Step 1: Extract files to specified directory (C:\CHI\cp210x44 in the example above).

  2. Connect the instrument to a USB port on your computer and turn the instrument on. Ignore and close any windows that appear automatically.

    Note: If during this step Windows Update insists on automatically installing a different driver version (6.x or higher), you will need to uninstall this driver manually as follows:
    1. Open Device Manager as in Step 3.
    2. Locate the "CP2101" device as in Step 4.
    3. (Optional) Determine the currently installed driver version as in Step 10 to be 6.x or higher.
    4. Right-click on the device and select Uninstall.
    5. In the "Confirm Device Uninstall" dialog box, check "Delete the driver software for this device" and click OK.
    6. Disconnect your computer from the internet.
    7. Disconnect and reconnect the instrument to your computer.

      This should prevent automatic installation of Silicon Labs driver version 6.x, which has been found to be problematic with newer Intel Core i3/i5/i7 motherboards.

  3. Click the Start orb in the lower-left corner of your desktop and type "device" in the search field. Click on Device Manager in the search results.


    Step 3: Open Device Manager.

  4. In Device Manager, double-click on a device marked with a exclamation mark and named "CP2101 USB to UART Bridge Controller" or something similar; this should be located under the "Other devices" or "Universal Serial Bus" category.


    Step 4: Locate and double-click on CP2101 device.

    Click the Update Driver button circled above.

  5. Select "Browse my computer for driver software".


    Step 5: Do not search automatically for drivers.

  6. Specify the extraction directory from Step 1 and click Next.


    Step 6: Search for drivers in the extraction directory from Step 1 (C:\CHI\cp210x44 in the example above).

  7. Click Install when presented with a security warning.


    Step 7: Trust CH Instruments, Inc. as a publisher.

    Silicon Labs wrote the driver; all we (CH Instruments) did was sign it (i.e., vouch for it; see Notes).

  8. Windows will now proceed to install driver files, resulting in the following window when complete:


    Step 8: Driver files installed.

  9. Repeat Steps 4-8 until the "CP2101 USB to UART Bridge Controller" device no longer shows up with an exclamation mark:


    Step 9: Driver installation complete.

    Two new devices should now be present in Device Manager: a "CP210x USB to UART Bridge Controller" under "Ports (COM & LPT)", and a "USB Composite Device" under "Universal Serial Bus controllers".

  10. Double-click on the "CP210x USB to UART Bridge Controller" device under "Ports (COM & LPT)" and verify that USB driver v4.4 is installed, working correctly, and signed by CH Instruments.


    Step 10: Verify driver status.

    This completes driver installation. Take note of the COM port number (COM4 in the example above). Assign this number in your instrument software, using the System command under the Setup menu, and then run the Hardware Test command under the Setup menu to confirm that the instrument and computer are communicating properly.