05-09-2014 03:31 PM
I have been trying to read temperature from a thermocouple in labview and dont understand what is wrong. I followed this example:
http://www.ni.com/white-paper/14338/en/
and you can even see the output from their example is reading -100 to 100 which cant be an accurate temperature. I have the two thermocouple leads plugged into a channel on a DAQ 6009 and it is just reading noise varying from -20 to +20 and doesnt read a temperature. I found an NI example VI in the example finder and it reads the same noisy -20 to +20 my original VI was. Is there something I am missing about how to properly hook a thermocouple up to the DAQ. Is it more complicated than just plugging in the two leads like their example shows? Any help is greatly appreciated.
My thermocouple is hooked up exactly like the wiring is displayed in that example and my Vi was simply the DAQ assistant set up just like their DAQmx and the output writing to a graph to see the data. Please help me turn this into usable data.
05-09-2014 03:52 PM
What you missed is how a USB 9213 differs from a USB 6009
the 9213 provides the correct scale for the thermocouple type as well as a cold junction reference. It also has a different pinout so if you hooked up Pins 2-20 you are very wrong
And yes they used a simulated device for the screenshot which is alwasy going to simulate a sine wave of full range (don't worry they didn't alternatly cook and freeze the developer ):smileyvery-happy:
05-09-2014 04:56 PM
So is there a way for me to set up a circuit to scale the input voltage from the thermocouple to get accurate temperature data without have to get a whole new DAQ device?
05-09-2014 08:17 PM
Consider a thermocouple amplifier such as the AD594 (Type J) or AD595 (Type K). They generate an output of 10 mV/degree C.
Lynn