However, the NI 9225 is calibrated at the factory to a NIST calibration reference. Offset and gain values for each channel are stored in an EEPROM on the module. When you read using Calibration Mode = Calibrated, the module applies this NIST calibration scaling for your voltage reading. This dramatically improves the accuracy of the module. Therefore, I recommend against using the RAW integer reading mode with this module.
You can find a shipping example for the module here:
If you do want to read in Raw integer and do the scaling yourself, you can use the FPGA I/O Property Node to read the LSB Weight and Offset values for each channel. Then follow this online help topic (Converting and Calibrating CompactRIO Analog Input Values) for instructions on how to do the conversions.