How do you use a Thermocouple with labview and a DAQpad-6020E?

[ddigregorio]

When I Connect my T-type themocouple to the Daq Devices I get incorrect readings. Is there something that I need to do with the Thermocouple before the input to the DAQ?

[Russell]

Hi there,

The main reason for the incorrect readings is that your VI is using wrong CJC values. The "Convert Thermocouple Reading.VI"'s CJC voltage input is expecting a reading from NI hardware specific CJC sensors. If you open this VI, you will notice that the first thing it does is convert this voltage back into a temperature.

First of all, I'll show you the fastest way to get up and running with thermocouples. This is to use a Virtual Channel that you set up through MAX. What Is a Virtual Channel? How Do I Create One? is a good Knowledge Base article. This will allow NI-DAQ to scale your thermocouple readings into temperatures so that the values that c
ome out of AI One Point will be temperatures. You can still do this programatically, but this is much easier.

Let me know if this isn't satisfactory.

Russell
Applications Engineer
National Instruments

[ddigregorio]

So, From a hardware perspective, would I need to use something like a SCC-TC0X?

[Russell]

Yes, the SCC modules are great especially if you anticipate you are going to need other forms of signal conditioning as well. If not, then an SCB-68 might be all you need. In order to use a SCC-TC0x you have to have an SC-2345 carrier too. The SCB-68 terminal block has an on-board CJC sensor and would be less expensive than an SCC-TC0x and SC-2345 together.

-Russell