RS232 will never die

I can't decide if it's a good thing or not that so many new hardware devices have an RS232 emulation mode. But here are some good tools suggested by Silicon Labs for debugging such things:

UVCView:

Microsoft: http://www.microsoft.com/whdc/device/stream/vidcap/UVCview.mspx

UVCView displays the USB information in a device (like VID, PID, Product String, descriptors, etc) connected to the bus. The driver for the device does not need to be installed or loaded for UVCView to read the information, as the utility uses the low-level USB driver to talk to the device. This is useful for when a CP210x is not enumerating because of an incorrectly programmed PID.

PortMon:

SysInternals: http://www.sysinternals.com/Utilities/Portmon.html

PortMon is a serial port monitoring program that records the transactions between the host application and the serial interface. PortMon is useful for determining if invalid settings are accidentally being used with the CP210x or if the data is being sent properly to the device.