Hello Bale-suk,
To convert the voltage you are reading into a pressure reading, you will need to scale the voltages according your sensor's specifications.
To do this, you have two options: Set up a custom scale in Measurement and Automation Explorer (MAX) or perform you scaling in your LabVIEW Application.
In MAX, right click on Data Neighborhood and select Create New... Then select Traditional NI-DAQ Virtual Channel and follow the channel wizard to set up you virtual channel. You will probably want to set this channel up as an Analog Input Voltage measurement. Select New Custom Scale when asked to "Define the Signal's Scaling." Enter the scale information from your transducer's specifications. Now, in LabVIEW, you c
an enter the virtual channel name, rather than the channel number, and the scaling will be done automatically.
To scale your voltage to pressure in LabVIEW, you would just have to make use of the Numeric Arithmetic functions to scale each value as it is read in. For example, if your voltage transducer measures 1.5 PSI/mV, then a voltage measurement of 2 mV would correspond to a pressure measurement of 2 mV * 1.5 PSI/mV = 3 PSI.
Let me know if you have further questions.
Sincerely,
Sean C.
Applications Engineer
National Instruments