The log I pasted doesn’t make much sense, I agree. I only logged a short time, until the application had updated both sensors, to hopefully make it easier to understand.
However, something is wrong right now, the application does not work anymore when I enable logging – the tray icon shows up, but the main form never does.
And I can’t kill the application – neither task manager or taskkill/F works, only a reboot.
Somehow the snoop filter seems to block the (inbound?) communication, so I’ll try to on another PC shortly.
I did get the “usb_control_msg” working in my own application, using the same values as the HID TEMPer in your code, and I *think* the internal sensor is being read exactly the same way in my HID temperNTC as the “standard” HID TEMPer:
The result from reading the temperature is a 256-byte array with the values “24 32 49 0 0 0 0 0 ” repeated.
24 + 32/256 = 24.125 degrees C – and that value changes to something like 28-30 degrees C when I hold the device in my hand.
So that is half the way to understanding the TEMPerNTC.
I’ve also used Reflector on the TemperNTC application, trying to get some hints, but unfortunately the actual readings from the device is handled by a non-DOT.NET dll, which Reflector cannot disassemble. I saw that the internal temperature is read by only one method call in the dll, so it makes sense that your code also does it in only one method call.
Getting the external temperature is quite more complicated – it seems like the application uses the DLL to read a voltage, dynamically adjusts some sort of gain, and finally uses a lookup table to find the current temperature based on the voltage/resistance characteristics of the NTC. So although it should be possible to snoop the USB communication, making sense of it will probably require tracing the execution of the application simultaneously…

Is the device you have this one: http://www.pcsensor.com/Thermometer/1-outer-NTC-sensor-thermometer/prod_27.html ?

Based on the software listing at http://www.pcsensor.com/software/info_5.html it looks like there’s a TEMPerNTC and an HID TEMPerNTC. Do you know which you have?

int usb_control_msg(usb_dev_handle *dev, int requesttype, int request,
int value, int index, char *bytes, int size, int timeout);

I am trying to convert the code to work on Windows, using LibUsbDotNet, but I am having difficulties figuring out the parameters used in usb_control_msg.

Using google I can only find calls to usb_control_msg with 9 parameters (eg. http://people.nl.linux.org/ftp/pub/anoncvs/kernelnewbies/documents/kdoc/kernel-api/r11386.html ), but your C-code has 8?
Could I kindly ask you to explain what the parameters mean – or perhaps provide me with a link?

Thanks in advance.