NI-9219 Incorrect RTD Measurement

[watlingd@colostate.edu]

Hello!

I am having some issues getting correct temperature readings from my 3-wire PT-100 RTD sensor connected to my NI-9219 DAQ. I have wired the sensor according to the back of the DAQ module with the two red wires in slot 3 and 5 and the red wire in slot 6. I have configured the NI-Max setup according to the spec of the RTD sensor, however when running it gives data points of -242 C at room temp and remains there even with added heat. I am unsure what could be causing these errors, the sensor is reading the 100 ohms at room temperature measuring it with a multimeter. Is there something incorrect in my setup?

I was able to read resistance measurements from the RTD by removing the red lead on slot 5 and replacing it with the white lead on 6. These measurements changed with added temperature, so I am really unsure why the RTD mode is not working.

[santo_13]

Your connections seem to be correct, and so is the DAQmx test panel configuration.

Have you tried a different channel? Ensure that the ferrule makes proper contact in the screw terminal.

[watlingd@colostate.edu]

Hello!

I have tried the other channels on the DAQ and it resulted in the same measurement of 242. I have also tested multiple of these RTD sensors, so the problem has to be DAQ related. I haven't tried increasing the length of exposed wire being placed into the channel, I will try that to ensure it is making proper contact.

Are there any other options that can be changed other than those in the DAQmx test panel that could be causing these issues? 

Thank you for your help!

[santo_13]

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watlingd@colostate.edu wrote:

Hello!

I have tried the other channels on the DAQ and it resulted in the same measurement of 242. I have also tested multiple of these RTD sensors, so the problem has to be DAQ related. I haven't tried increasing the length of exposed wire being placed into the channel, I will try that to ensure it is making proper contact.

Are there any other options that can be changed other than those in the DAQmx test panel that could be causing these issues? 

Thank you for your help!

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Try connecting a 100 ohm resistor instead of RTD, directly on the terminal block, pins 3,5 to one leg of resistor and pin 6 to the other. If correct, the DAQ should measure close to 0C.

In addition to DAQmx test panels, try the FlexLogger lite edition to confirm that software is not the problem.