DC Voltage Measurements Using Analog Input Modules for AC applications.

Updated Dec 13, 2023

Reported In


  • NI-9225
  • NI-9242
  • C Series Universal Analog Input Module


  • LabVIEW


  • NI-DAQmx

Operating System

  • Windows

Issue Details

Can I measure both AC and DC using a single analog input module with AC characteristics, such as NI 9225 or NI 9242 module?


Analog input modules focused on AC applications should be able to measure DC values, however, it is not recommended as they were not designed for this purpose. You should check if there is AC or DC coupling on the module from the datasheet. 

For example, the NI 9225 module is a 3-Channel, Simultaneous, Channel-to-Channel Isolated Analog Input Module. It can measure both AC and DC voltages. The NI 9225 Datasheet page 19 specifies that the NI 9225 has DC coupling and over-voltage protection of +/- 450 VDC, so there should not be any problem.

Additional Information

The NI 9225 analog input channels are floating with respect to earth's ground and each other. The incoming analog signal on each channel is conditioned, buffered, and then sampled by a 24-bit Delta-Sigma ADC.