MCC USB-2001-TC Raw Voltage Conversion to Temperature

[Hamza89]

Hello,

I have a type s thermocouple that is connected to the MCC USB-2001-TC unit, the thermocouple goes into an oven that can go up to 2700F. I Use LabVIEW to collect the data from the DAQ. I've tried to collect the temperature readings but whenever the temperature reaches ~1700F, the readings drop down to ~1400F and stay there until the temperature drops back down below 1700F. However, I tried to collect the raw voltage from the TC and those values seem to follow the temperature better, so I'm trying to convert the raw data to temperature but can't seem to find a way to do that. I've tried to follow the NIST Type S coefficient but the raw data is ranging between 632500.3 at 2700F and 524338 at 80F, which is way higher than the NIST mV ranges. Is there a way I can convert the raw data to temperatures?

Thank you,

[Fausto]

Hello @Hamza89.

Are you using an electric oven?  Typically, when we see measurements appear abnormal after reaching a certain temperature, the culprit is RF or EMF noise.  Also, if the thermocouple end is against a metal surface, then use a thin film tape or epoxy on the thermocouple tip.

When retrieving raw data from the USB-2001-TC, the underlying Universal Library uses the NOSCALE option.  According to the MCC Universal Library Help, when NOSCALE is used, calibrated data is returned, which falls within an input range of +/-73.125 mV.  Additionally, a cold junction compensation (CJC) correction factor is not applied to the returned raw values, but is returned with each raw data point.  Since, the raw values are not in millivolts, a temperature conversion is not possible.  

 

If you require additional thermocouple channels for your measurements, then consider the USB-TC device.

https://digilent.com/shop/mcc-usb-temp-and-tc-series-temperature-and-voltage-measurement-usb-daq-devices/

 

Regards,

Fausto