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Temperature Fluctuation Using USB-6501 DAQ

Hello All

 

I am attempting to measure a thermocouple with a USB-6351 DAQ. The hardware configuration I am using is an OMEGA Type K glass-braided thermcouple, connected to the USB-6351 DAQ using an OMEGA thermocouple extension cable TECK10  which has bare wires which insert directly on to the screw terminals on the DAQ. The specific screw terminals I am connecting to are shown below.

 

DAQ Set-up.png

I was seeing a lot of fluctuation when I was reading the thermocouples shown below.

 

Thermocouple Fluctation.png

 

I was hoping for some input on several things. If my hardware configuration is okay, it appears to be a solid connection I can pull on it lightly without any give. If the DAQ I have is okay for measuring these thermocouples. Do I need to be doing signal conditioning or anything within the program itself? Basically, just looking for some advice and tips to improve the quality of the data.

 

Thanks in advance!

 

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Joel,

 

Your wiring looks fine and typically loose connections manifest much worse than the noise you are seeing. One thing that sticks out to me, it's possible that the extension for your thermocouple wire may be introducing noise into your measurement. Can you try a measurement without the extension? 

Austin
Product Support Engineer
National Instruments
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Hi,

Im having exactly the same problem (http://forums.ni.com/t5/Measure/Measuring-temperature-with-NI9215-and-TC-type-K/td-p/3642340), but I'm using a NI 9215 module. I think it is because my NI module is no suitable for thermocouple measuring because of its range of measuring of +-10V, therefore the module doesn't detect the signal from the thermocouple in uV.

 

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