Connection Issues With Silicon Labs CP201x - MD100A12, MD100I2, MD300W, CMS50EW, CMS50FW

Silicon Labs CP210x USB to UART Bridge is commonly used in many medical monitors, such as MD300I2, MD300W1, MD100A12, CMS50E, CMS50FW, and CMS50EW. Occasionally customers reported problems when connecting these devices to the computer. Here is is list of the most common ones, starting with the simplest one to resolve to the "impossible" ones.


USB connection: Make sure that the USB connector is firmly plugged all the way into the device. Sometimes it may take an excessive amount of force to push it in. Do this a few times and the problem should disappear.

Power: The device must be powered on and connected to the computer prior to starting the management software. Some software tries to establish a connection when it starts and if fails, it will not try again.

Power: Make sure the device is powered on during the entire process. Some devices may shut off automatically due to inactivitiy.

CP210x driver download: You can download a copy of the driver from this website.

Driver installation: Make sure the driver is installed properly. When the device is plugged in, you should see an entry "Silicon Labs CP210x USB to UART Bridge (COMx)" under "Ports (COM & LPT)." "COMx" is the COM port assigned to the device. With MedView (MD100A12, MD300I2...), you can set the COM port manually to the one listed in Device Manager.

When you unplug the device from the computer, the Silicon Labs entry should disappear from Device Manager.

See next section on how to reinstall the driver.

Windows driver signature enforcement: Later versions of Windows would prevent the driver from being installed as it is not digitally signed. To get around this issue, disable the driver signature enforcement before installing the software.

To disable this feature in Windows 8:

  • From Charms bar, select Settings >> "Change PC settings" >> "General" >> "Restart now" in "Advanced startup" section >> "Troubleshoot" >> "Advanced options" >> "Startup Settings" >> "Restart". The computer would restart.
  • During startup, select the "Disable driver signature enforcement" option.

Another alternative is during system reboots and before Windows starts, press F8 key to bring up the Advanced Boot Options menu. Then disable driver signature enforcement manually.

Windows compatibility: A customer reported that the software ran better in XP compatibility mode. Right click software icon >> Properties >> Compatibility tab >> Check "Run the program in compatibility mode for" and select Windows XP in the dropdown list.

Software installation: Something happens during installation or the CD containing the software is defective.

If the CD is defective, contact your supplier for assistance. See next section on how to reinstall the software.

Software conflict: If a conflict exists, there is an error message, such as "Read COM error" or "Cannot connect to device." When two or more programs trying to talk to USB ports, they may interfere with each other. There are two methods to resolve this problem:

  • Find out which program is causing the conflict and then uninstall the program. Run these programs at the same time and see which ones are having problem. A telltale sign is error message during system start-up or when the program is running
  • Avoid the issue by running the device software on another computer or environment. There are several ways one can create multiple environments on a computer. They are:
    • Run the device software in a clean copy of Windows Virtual PC or VMware.
    • Install multiple operating systems (multi-boot) on the same computer and run the device software on the "clean" one.
    • Install Windows on an USB drive and boot the computer from the USB drive.

Reinstall software and driver

Prior to do any re-installation, remove all existing drivers and software. This is critical; otherwise the re-installation would fail.

Remove existing software and driver

  • With the device connected to the computer, remove the driver from device manager. Right click on computer >> manager >> device manager >> Ports >> right click Silicon Labs... >> uninstall.
  • Unplug the device from the computer.
  • Go to "Uninstall a Program," uninstall the device software and Silicon Labs driver. You may find multiple entries for the Silicon Labs driver; uninstall all of them.
  • Reboot the computer.

Software installation

Follow the instructions that come with the device, run the setup program. Pay attention to the message prompt. In one installation, the default is not to install the driver.