Hi, 
 
I tried to run a sample program given in the following directory,
 
\National Instruments\NI-DAQ\Examples\DAQmx ANSI C\Counter\Generate Pulse\Dig Pulse Train-Cont-Buff-Implicit,
 
which is a buffered pulse output program with pre-determined duty ratios.
However, an error says that the counter writing function cannot be started before the task is started.
 
I am using USB-6281 M-series DAQ. Is this sample program not suitable to my device?
How can I then use such pre-determined duty arrays or real-time duty updates?
 
I am really looking forward to hearing from you..
 
Thank you.
 
Byeong-uk, Im.