Data acquisition of thermister using NI devices

[HYPENG]

Hello,

I am relatively new to data acquisition and currently working on a project to measure temperature using Omega's 2-wire thermistors, specifically models SA1-TH-44004 and TH-44033.

Our lab has several NI devices, including the NI 9205, NI 9263, NI 9264, NI cRIO-9073, NI Cdaq-9178, and NI USB-6210. We also have the NI 9213 and NI 9217 modules, but it appears that they only support thermocouples and RTDs.

Could you kindly advise if any of these devices are suitable for acquiring data from thermistors? If so, could you provide guidance on how to properly connect the thermistors to the device?

If none of these devices are compatible, I would greatly appreciate any recommendations on a suitable NI device and the proper method for connecting the thermistors for data acquisition.

Thank you very much for your assistance!

Best,
HY

[Ahmed99]

Yes you can , If you choose to use the 9217, you’ll need to modify the scaling of the measurements, as this is an RTD module. If you have LabVIEW you will need to create an RTD channel, choose a custom RTD type (bottom terminal on Create Channel VI) and then use a channel property node (AI » Temperature » RTD » Custom » A, B, and C) for the scaling.

If you chose to use a 9213, you will see that the thermistor task type is integrated into the DAQ assistant (such as used when setting up a task in Measurement & Automation Explorer (MAX)).

Please post back if you have further questions. Good luck!

[santo_13 · Accepted solution]

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@Ahmed99 wrote:

Yes you can , If you choose to use the 9217, you’ll need to modify the scaling of the measurements, as this is an RTD module. If you have LabVIEW you will need to create an RTD channel, choose a custom RTD type (bottom terminal on Create Channel VI) and then use a channel property node (AI » Temperature » RTD » Custom » A, B, and C) for the scaling.

If you chose to use a 9213, you will see that the thermistor task type is integrated into the DAQ assistant (such as used when setting up a task in Measurement & Automation Explorer (MAX)).

Please post back if you have further questions. Good luck!

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9217 will not be able to properly measure the thermistor due to its high resistance (2252 ohm at 25C) and the 9217 supports only upto 400 ohm load.

[HYPENG]

Thank you for your previous response. Based on your suggestion, I chose to use the NI 9213 for my project.  I was able to successfully acquire thermocouple data with this module. However, I am experiencing issues while attempting to acquire data from thermistors.

Here is what I have done so far:

In DAQmx, I select my device under "Devices and Interfaces," then create a task and add a channel.

It seems that only when I select "Iex thermistor" and set it to "external excitation" am I able to run it without errors.

After inputting the Steinhart-Hart parameters based on the thermistor's specifications, I am able to get readings from the TH-44033, while the two TH-44004 thermistors show the same values as if no sensor is connected. Additionally, the readings from the TH-44033 are unusual and differ significantly from the thermocouple readings.

Could you please advise where I might be going wrong?Is this an issue with wiring, or could the parameters be incorrectly set?

I am also trying to use FlexLogger to capture and log the data, but the sensor class only seems to allow settings for thermocouples and voltage. How should I configure FlexLogger to capture thermistor data accurately?

Thank you so much for your help!