Jamie,
I took a look at the example that you were referencing, and now understand your confusion. The example that you posted is a program that was probably designed to be used with one of National Instruments' data acquisition boards. Data acquisition boards usually have multiple channels, and these can be used to take multiple thermocouple measurements. Because this is occurring at room temperature, an adjustment has to be made. In order to do this, we devote one channel of the data acquisition board to measure the value of room temperature and then adjust all the other channels accordingly. (Most of our newer data acquisition boards have built-in CJC, and can handle this automatically).
In your case, you are using a DMM, so you have only one channel. With only one input channel, it will not be possible to devote a channel to Cold Junction Compensation. Instead, you have a couple of options that I can think:
1. You can allow the user to select the room temperature (as you are doing now).
2. If you are using your DMM in conjunction with a switch module, then you could devote one channel to measure the room temperature. This would work similar to the example you posted, but would require some additional programming to work with the switch.
3. You could move to a different measurement device, like a data acquisition board, that has extra channels or built-in cold junction compensation available.
I hope that helps to clarify what is happening with CJC. If you have any additional questions, please feel free to post back.
Regards,
Jed R.
Applications Engineer
National Instruments
