Rob
The better way to approach the problem is by creating a virtual channel at Measurement and Automation Explorer (MAX).
MAX will allow you to convert the voltage reading at your DAQ input channel into a valid physical number, by scaling the voltage reading.
To create a virtual channel, open up MAX, go to Data Neighborhood, right click at that option and choose create new. Then, choose the option Virtual Channel and follow the steps. It's pretty straight forward. Then you can create a scale that will translate the voltage reading to a physical value.
After that, you can open the Labview example named Continuous Acquisition and Chart Buffered.vi, and, instead of typing the channel number in the channel field, you can type in the virtual channel number you've crea
ted with MAX, then the chart will display the db value instead of the channel number.
You can find that Labview example at: Search Examples->I/O Interfaces-> Data Acquisition->Analog Input-> Continuous Analog Input.
Hope this helps.
Filipe