Upon closer examination, I found that the converter cable on my KPC3 is from RT Systems. I searched the RT System website and was unable to find it at this time. It has an FTDI chip within the USB connector.
Google would not let me attach the driver. It is available on RT Systems website.
Name: USBComDrivers21.exe
RT Systems provides excellent support. You could try calling on Monday. Another alternative is HamMadeParts.com
Maybe this will help.
73, de Jeff G. WD4ET