Obtaining the latest drivers for use with Davis data loggers
When using a Davis Instruments USB data logger, you need to install the Silicon Labs USB-serial bridge driver into MacOS. The driver package can be found here: USB to UART Bridge VCP Drivers. I would not try getting them from the Davis site; they have been reported to not keep them up to date.
When you upgrade MacOS to a new major version, you will normally need to upgrade the Silicon Labs serial driver.
If you are having difficulties connecting to your station using WeatherCat, check the WeatherCat support forum to determine which version of drivers are needed for your system and Davis hardware, and where to obtain them. It may also be useful to review the release notes from Silicon Labs (found inside the installer zip files).
Note: Installing the Silicon Labs driver directly is at your own risk as it is not supplied by Davis.
Follow the instructions for downloading and installing the drivers. The driver will prompt you to grant permission in System Preferences and give you a button that leads to the right place. I strongly recommend doing this when prompted during the driver installation. It can be tricky to find later, and as of Catalina there is a 30 minute timeout window for you to do it.
Upon successful installation, older MacOS versions may need to be rebooted manually (no longer needed in Catalina and Big Sur).
After installing the driver, WeatherCat should be able to successfully connect to your Davis station data logger. To do that, select it in the communications window in WeatherCat as shown below: