Error -200431: Selected Physical Channels Not Supported

Updated Mar 7, 2024

Reported In


  • CompactRIO Controller


  • LabVIEW

Issue Details

  • I would like to measure the frequency and the duty-cycle of a PWM-Signal (Pulse Width Modulated Signal) using a single physical channel and a single counter. Reading the high time and low time measurements of the signal with a single physical channel and a single counter would also be suitable for this purpose. I get the error message with the code -200431 in LabVIEW, if I try to use either of the CI-Pulse Freq, CI-Pulse Time or CI-Pulse Ticks variants of the DAQmx Create Virtual Channel vi together with the physical channel of the NI 9361 Counter Digital Input module in a CompactDAQ or CompactRIO chassis.
  • I get error -200431 when using simulated PCI-6602 as counter input in DAQmx Create Channel (CI-Pulse Freq).vi 


There are two possible solutions to the problem, both require modification of the hardware configuration:
  1. Use the NI 9361 Counter Digital Input module together with a CompactRIO system. The NI 9361 supports pulse measurements only for CompactRIO systems.
  2. Use NI 9402 or any counter that is capable of measuring pulse frequency.
  3. Alternatively, look at cDAQ Module Support for Accessing On-board Counters.
With either of the above modules, it will be possible to measure duty cycle with a single counter using a single physical and virtual channel.

Additional Information

Each PWM measurement requires one counter at least. The number of parallel PWM readings you can perform will strictly depend on the number of counters available in your cDAQ. Please refer to the specific DAQ Series Manual for more detailed information about these types of readings.