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NI-PXI 6030E Thermocouple Temperature
EngineeringEE
06-04-2011 09:28 PM
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Hello all,
I am trying to measure the temperature of a bath filled with saline @ 85C with a K-type thermocouple. I am running Labview 7.0 with a NI-PXI 6030E. What is the best way to get an accurate reading? Are there any equations of examples out there that can do this for me? I tried the example given by labview to take a temperature reading with a thermocouple but it does not work. Another question is I do not have cold junction compensation. How can I set up my system to do this for me?
Thank you,
S.L.
06-06-2011 02:48 PM
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Hi S.L.
How are you connecting your thermocouple? Are you using a breakout board? If you do not have CJC, you will have to set the CJC source to Constant and set the CJC value that corresponds to the ambient temperature of the connection screws on your PXI board. You specify these parameters in the Create Task function of DAQmx.
What about the example you used doesn't work? Do you recieve an error or are you getting unexpected values? What example are you using? Are you using tDAQ or DAQmx functions?
With thermocouples, there is set accuracy for each different type. I've linked that here.
Make sure your wires are connected to the right +/- terminals. You can double check your color coded connections here.
Allie
06-11-2011 05:00 PM
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Sorry for the delay.
I am using a keithley 2000 meter to read the temperature. The keithley is connected to the computer through RS232. A K-TYPE thermocouple is being used. The first problem I have is I get a +800 error. I want Labview to grab the measurement from the keithley and output it to a file. I need Labview to take a temperature measurement every 10 minutes.
On a side note:
Does anyone know the equation to convert a resistance or voltage reading from a thermocouple to a temperature?
Thank you for your help!
06-13-2011 03:08 PM
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If you're using Keithley, then your application will be seperate from your DAQ device. You'll need to use VISA calls for serial communication. See the example here: http://zone.ni.com/devzone/cda/epd/p/id/3631
Here's more information about converting the thermocouple voltage to a temperature. http://mosaic-industries.com/embedded-systems/05-app-notes/temperature-measurement/using-type-k-ther...
Kind Regards,
