This summer I purchased some TemperHum devices from DX. The goal was to track humidity and temperature levels and store the results in a database using my own software. It was sort of a summer project, but I never got around to finishing it. The included software didn’t work properly on 64bit Win7, but I found the ThermoHID freeware that worked most of the time. It froze about once a week, but at least I had readings. It didn’t support database exports though, and I still wanted to write the software myself
The manufacturers site clearly states that writing your own software is possible, but the details were at best sketchy. Searching revealed that I was not the only one with trouble connecting to these devices. One of the main issues seems to be that there are several versions that look exactly the same. To be specific, the version I have is detected by Windows as hardware id 1130, PID 660C. Furthermore you have to interface with a DLL from the manufacturer, for which I have yet to find an official API. This also exists in several versions. The one I’m using is called HidFTDll.dll, is 176 194bytes and last modified 2009.08.29.