voltage temperature calibration

[ylazybug]

hi I'm not familiar with labview but working my way through it because of a school project.

I'm using DAQ and an analog temperature sensor module. I've seen that it works through the graph but I'm unsure of how I'm supposed to use this information and change it into temperature values. Thanks for your help!

[GerdW]

Hi bug,

at first: please don't use non-ASCII letters in filenames.

Computers outside of Corea (atleast in Europe/Americas) will have problems to open such files!

How do you connect that thermistor to your DAQ device? Which reading do you get?

Usually you use a voltage divider (or bridge) with (atleast) one additional resistor: then you read a voltage. Applying Kirchhoff's rules you can calculate the resistance of the thermistor in your circuit. With this value you can look up the corresponding temperature from the given table… (Or you use an exponential equation to calculate temperature from resistance.)

[ylazybug]

I reuploaded the vi and images with an image of my sensor module!

Right now I get a waveform amplitude/time and checked the sensor works fine but I'm unfamiliar with calibration ;(

I'm guessing connecting a convert thermistor/thermocouple( voltage to temperature) won't work so I'm figuring out how to get the data in temperature(degrees form), again I thank you for your help

[RTSLVU]

What is that device you are using? Did it come with any documentation explaining how to use it? 

If this device outputs a DC voltage proportional to the temperature measured then the documentation should give you that ratio (such as 10mV/degree C)  or a conversion factor.

Without that we can only guess... 

[ylazybug]

the only information I've got is that the resistance value changes depending on the temperature value. The file I uploaded on my first thread is what I believe is the change in resistance as temperature changes. the sensor was originally for arduino users, so the manual doesn't really tell me much

[RTSLVU]

Every thermistor changes resistance with temperature.

What's it's base resistance? But at what rate does it change? Positive or negative temperature coefficient?

That device is more than a thermistor so the manual even if it's for an Arduino should give you all the information you need.

[ylazybug]

Truly the pictures I uploaded are the only information I have about the sensor module. It's in Korean but it just talks about how it motions and what the output voltage is 😞 

[GerdW]

Hi bug,

there needs to be more information available!

When that part is used as Arduino add-on then there probably is a driver (for Arduino) available. This driver allows to read the sensor data: which kind of result does it deliver? Does that driver include methods to convert thermistor reading into degreeC or Kelvin?

In the end all you need is a good manual for your device. When that supplier cannot provide such a manual you should choose a different supplier!

[ylazybug]

we're only allowed to use the given sensor modules so I'm stuck with this one 😞 even though the sensor was in an arduino kit we use the sensor with our daq to connect it with labview. The sensor outputs an analog voltage from 0-5V depending on temperature and I've checked the change in amplitude when temperature rises. I'm trying to use this sensor to turn on a set of leds when the temperature rises above a certain amount, so I need to be able to calibrate the data into temperature while using the given sensor, daq and labview 😞

[RTSLVU]

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@ylazybug wrote:

we're only allowed to use the given sensor modules so I'm stuck with this one 😞 even though the sensor was in an arduino kit we use the sensor with our daq to connect it with labview. The sensor outputs an analog voltage from 0-5V depending on temperature and I've checked the change in amplitude when temperature rises. I'm trying to use this sensor to turn on a set of leds when the temperature rises above a certain amount, so I need to be able to calibrate the data into temperature while using the given sensor, daq and labview 😞

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Well you need to tell your teacher that they have not given you enough information to complete the assignment. You need to know the volts/degree scaling this device outputs.

If part of the assignment was to figure this out. You need more equipment like at minimum a calibrated thermometer and a cold/heat source. Then you can manually test a number of temperatures points and figure out how the output voltage correlates. I hope for you sake its response is linear in the range you need it 😛