To configure the FPGA I/O Node to accept calibrated, fixed-point data in units of volts for the onboard analog output module, set the Calibration Mode to Calibrated in the Module Properties dialog box for the module.

When Calibration Mode is set to Raw, the FPGA I/O Node accepts only binary values. Convert output voltage values to binary values using the calibration constants before writing them to the FPGA I/O node. The conversion of voltage values to binary values can be done in the host VI.

Using an Equation to Convert Voltage to Binary

Use the following equation in the host VI to convert the analog output values to binary values:

Binary Value = (Voltage Value - Offset) ÷ LSB Weight

where

  • Binary Value is the value you write to the FPGA I/O Node.
  • Voltage Value is the voltage in V that you want the channel to output.
  • Offset is the value returned by the Offset property.
  • LSB Weight is the value returned by the LSB Weight property.
The LSB Weight property is returned in units of nV/LSB. The Offset property is returned in units of nV.
NI recommends using calibrated values for analog output. To convert calibrated voltage values, use the FPGA I/O Property Node to read theLSB Weight and Offset properties. If you do not want to read the LSB Weight and Offset values from the module, you can convert uncalibrated voltage values by using the following typical values for Offset and LSB Weight:
  • Offset = 0 V
  • LSB Weight = 320 µV/LSB