USB TC-01 showing incorrect temperature on some PCs

[OllUoL]

Hello,

I haven’t posted on these forums before, so sorry if this isn’t in the right place.

I have a USB TC-01 temperature recorder hooked up to a K type thermocouple. This is plug and play, although I will be using it as part of a larger VI I’ve written.

It is behaving rather oddly. When I plug the USB TC-01 into my desktop PC (HP Elite desk) the recorded room temperature reads about 30 ⁰C too high (around 60 when it is 30). This is showing on the Plug and Play software, not any VI I have written.

If I plug this into an alternative PC then the unit records the correct temperature.

Unfortunately I can’t easily swap PCs as I have specific software installed etc.

I have reinstalled the USB drivers for the PC, and the keyboard and mouse and other USB hardware works fine.

Any advice on how to fix this would be appreciated.

Thanks very much,

Oliver

[NataliaS]

Hey,

Interesting problem you have there, is it still happening?

Since the device is working correctly on a different PC I am wondering what is the difference between those?

What kind of USB port are you using, have you tried swapping those?

-Natalia

[OllUoL]

Hello, 

Thanks for your reply. 

After much switching around, we realised that it was actually an even odder probelem than we thought. A dc power suplly was causing some current to go to the earth of the the frame, which was picked up by the thermocouple somehow. electrically isolating the thermocouple from the frame seemed to fix the problem. The problem manifested itself differently on different PCs, which is bizzare. But it's all fixed now. 

Thanks again. 

[AnalogKid2DigitalMan]

Good detective work on discovering the problem, Kudo for you!

-AK2DM