Error -201002 or -200303 When Doing Buffered Event Counting with DAQmx

Updated Jun 20, 2023

Reported In


  • cDAQ-9174
  • NI-9402
  • C Series Counter Input Module


  • NI-DAQmx

Issue Details

I get error -201002 when using the internal timebase as the clock source for my buffered event counting task, as shown below.

If I change the clock to OnboardClock, as the error message suggests, I get error -200303, as shown below:

Why can't I use an internal or onboard clock for this application?


Buffered event counting tasks always require the use of an external clock source. Error -201002 occurs because, unlike with analog tasks, buffered counter tasks cannot divide down the internal or onboard clock. 

You can use another counter to generate a pulse train to be used as the clock for the buffered event counting. The Community Example Use Counter to Create a Clock for a Buffered Edge Counting Task  demonstrates this.  If using cDAQ, you can also use the sample clock from an AI, AO, or DIO task as the external clock.