mwall, as I've stated before, the cp210x driver can not handle the ioctl requests TIOCGSERIAL and TIOCSSERIAL which many serial communication clients use and the fallback in the tty driver seems to not allow the baud rate 128000 to be set. The baud rate can however be set with other ioctl requests but the pyserial module that works with the older versions of Python, for example 2.7.3, uses the ioctl requests that are not supported by the cp210x driver.
Python is not a problem here but the version of the pyserial that works may have a minimum version of python required which creates a dependency. The cp210x kernel driver is problematic in the way that it doesn't handle the ioctl request above. The actual problem I would say is the 128000 baud rate which require us to make work arounds and have a matching combination of serial communication client and kernel driver. I still have to try the modified kernel driver that I've linked to in a previous post. From the weewx perspective is better to have a kernel driver that works with the weather station and not require a specific version och pyserial. Ofcourse, just requiring a minimum version of pyserial is the least effort to make it work. Now I want to spend some time using your weewx driver and get familiar with the weather data and verify that it matches the WMR89 display.
