thermometer VI confusion

[vcat2k]

I was going through the online tutorial for Thermometer VI and I was wondering what it meant when it talked about having a temperature sensor connected to the computer. I was wondering if I could open up the daq board 6016 and connect a voltage supply to the pins on the board to get readings for temperature since it is really converting voltage readings to temperature readings. I also wanted to know whether it is possible to any intrumentation device up to teh daq board to get readings from it. I assumed the way it works is that the computer is connected to the daq and the daq is hooked up to the device.

[hannahW]

Hi,

There are quite a few tutorials on the ni.com website which discuss temperature measurements, so I'm not sure which exact one you are referencing?

To perform a temperature measurement you will need some kind of sensor, like a thermocouple, to connect to your DAQ device. The thermocouple will return a known range of voltages in direct relation to the temperature of the place you measure.

The USB-6016 provides screw terminal connectivity for the signals you want to measure, so you can wire sensors into the terminals on the front of the device. Connecting a thermocouple typically would require some sort of signal conditioning, as the voltages returned are very small, and often need to be ofset by a CJC temperature. Without signal conditioning however you can wire analog and digital signals into the device within the specified range, and read these.

What is it you are trying to do with the USB-6016? Do you want to measure temperature or are you using this as a getting started case? If you can give me some more information, perhaps I can point you in the direction of some more helpful tutorials?

Regards
Hannah
NIUK & Ireland

[vcat2k]

There was a tutorial on the thermometer vi on cnx.org and I thought that since the device is really reading votlage, it might be possible to get the same  response as hooking up a DC power supply to the unit. But when I added a tiny amount of voltage to the circuit the temperature readings shot up to close to 1000 F. Initial temperature without any hook up to the device is like 71 F. How do I account for the strange readings. In addtion, the connection diagram told me to hook the DC power to pin 1 and 2. On the reference connection diagram none of those pins are ground.

I am also a new to labview. My supervisor for this internship wanted me to learn how to use it. Thanks for the response 🙂

I hope to get more insight as to how to go about this. Could you recommend a good book for learning labview and the daq board?

[hannahW]

I had a look on the cnx website, and I think you mean this tutorial: http://cnx.org/content/m12209/latest/ although I can't find any connection information in here.

This tutorial is designed to be done using a signal accessory device that we use in our training courses. This device is basically a set of sensors built into a box, including a temperature sensor.

The sensor in this box returns a voltage between 0 and 1 volts which relates to temperature readings between 0 and 100 degrees C. So if you supply a voltage of 0.1V then the thermometer vi in tutorial you should get a temperature of 10 degrees C. This could explain the large readings you are seeing if you are supply larger voltages into the USB-6016.

Also - to connect a voltage source to ai0 of the 6016 you will need to wire the positive signal into pin 1 and the gound/negative signal into pin 24 which is the ground of the device.

There are loads of tutorials and manuals on the ni.com website. I would start off by looking at the following manual:
http://digital.ni.com/manuals.nsf/websearch/352B52F168FDA35F86257199006B7144

If you want more in depth information and tutorials on LabVIEW - check out the training courses that NI offer, there is also some training material online:
http://www.ni.com/training/

I hope this helps

Regards
Hannah
NIUK & Ireland