thermocouple detection

[Janiece]

I am attempting to measure a thermocouple (type k or type t, ambient to 300C) with a SCB-68 breakout box connected to an AT-MIO-16XE-50 card using Labview 6.0. I know how to set the S3 S4 and S5 switches to power the cold junction sensor on the break out box ("IC Sensor"??), but I need to know how to get the sensor reading to a port such that it can be read by the labview subVI for thermocouple detection (thermo linear) CJC Voltage input.
I also need to know how to connect AI signals to the onboard amplifier (how do the high and low limits that are inputs to the subVIs relate to the amplifier?).
I will likely be setting up the system to measure the two thermocouple leads differentially.
Any assistance would be helpful
thank you

[Laura F.]

Hi Janiece,

Once you have the switches configured such that the CJC is active and your SCB-68 is cabled to your DAQ device, the CJC voltage will be read in on channel 0 as described in the SCB-68 User Manual. To find out what terminals on your SCB-68 correspond to which lines on your MIO-16XE-50, check out the E Series Help where you can find the pinout for your device. In order to do a differential measurement, you will want to put the positive lead of the thermocouple in a channel (AI 1), and then put the negative lead in that channel number plus 8 (AI 9). You can see by looking at the pinout that channel AI 1 is pin 33 on the SCB-68 and AI 9 is pin 66. You can find examples on how to thermocouple measurements in LabVIEW by going to Help >> Find Examples and then on the search tab, search for thermocouple. The high and low limit inputs into DAQ VIs are used to set the gain of the amplifier. You will want to specify the smallest range possible to get the most resolution, which is important for thermocouple measurements.

Regards,
Laura