I have a PXI-6602 and am writing a C++ class to control the card. I am experiencing an issue when using ctr0 for edge counting. My setup includes one PXI-6602 and a BNC-2121. I'm using the continuous pulse signal as the source signal to the counters. My software execute the following functions in order.
// Clear any old tasks
DAQmxClearTask( TaskHandle );
// Create new task
DAQmxCreateTask( "ctr0Task",
TaskHandle );
// Setup channel
DAQmxCreateCICountEdgeChan( TaskHandle,
"\CTR1\ctr0"
"",
DAQmx_Val_Rising,
0,
DAQmx_Val_CountUp );
// Start Task
DAQmxStartTask( TaskHandle );
// Read counter value
DAQmxReadCounterU32( TaskHandle,
DAQmx_Val_Auto,
10,
buffer,
sampsRead,
NULL );
I execute the above code and let the task run for approximately one second. I read one sample of zero (0) counts on ctr0. When I execute the same code for the other counters, I read around 464 counts, which I believe to be valid.
Why am I reading zero counts on ctr0?
I have tried the following:
1) Using the Test Panel, I setup ctr0 for edge counting and used PFI39 (ctr0Source) as the source signal and everything worked as expected. So I know the hardware is working. I also selected the 20MHzTimebase signal as the source and everything worked as expected.
2) I manually setup a task within NI-MAX and everything worked as expected.
3) Within my software, I routed the 20MHzTimebase signal to ctr0 source and received counts although the value was incorrect. No matter how long I let the task run, I would only read around 260 counts. When routing the 20MHzTimebase to one of the other counter's source, everything worked as expected.
4) I also routed PFI39 to the source of the other counters and everything worked as expected.
Is ctr0 special or reserved? Does it have a unique timing characteristic that I'm unaware of?
Thanks in advance for any help.
-Mroche
