Synchronization of multiple tasks?

Question

Hello,
I am currently working on a project that requires analog output signals and counter tasks to be synchronized.  The board I am using is the NI-6363 X series.  I am doing this in C++.
I called the start tasks one after the other, and then the read code like this:
DAQmxStartTask(taskHandlAO);
DAQmxStartTask(taskHandlCtr1);
DAQmxStartTask(taskHandlCtr2);
DAQmxReadCounterU32(taskHandlCtr1);
DAQmxReadCounterU32(taskHandlCtr2);
The AO clock and the counter read clock are driven by the same digital signal obtained by dividing the 20Mhz master time base using another counter.
Obviously the software timing delays between the start tasks and the read functions are causing my results to be inaccurate.
Is there a way i could group all the tasks together and force them to start at the same time?
Thank you in advance.
HT

Answer 1

Hi John,
Thanks for your timely reply.
I am using two counters to perform buffered counting edges in TTL pulse inputs.  I tried to start the clock source after all the tasks but there is still a problem.  Here's an updated snipet of my code:
DAQmxStartTask(taskHandleCtr);
DAQmxStartTask(taskHandleCtr2); 
DAQmxStartTask(taskHandleAO);
DAQmxReadCounterU32(counter1)
DAQmxReadCounterU32(counter2)
DAQmxStartTask(taskHandleClk); //Clock source
In theory none of the first three tasks would not start until the clock got started which would mean they would all be synchronized.  However the program seems to be stuck waiting for a measurement in the DAQmxReadCounterU32 function and never even reaches the start task code for the clock.
If I change rearragne the code to look like this:
DAQmxStartTask(taskHandleCtr);
DAQmxStartTask(taskHandleCtr2); 
DAQmxStartTask(taskHandleAO);
DAQmxStartTask(taskHandleClk);
DAQmxReadCounterU32(counter1)
DAQmxReadCounterU32(counter2)
The program would run but the time delay between the start clock and DAQmxReadCounterU32 functions would cause the same problem i had initially.
The results are inaccurate because the analog output tasks are driving scanners, if the analog output tasks were started before the counter tasks, the counter tasks would record counts that corresponding to the wrong scanner position and there would be no way of telling how much the results were shifted by.
I took a look at the Arm Start Trigger section of the manual, but I am confused as to where I would find this signal (external source?) to trigger the tasks and if there is a specific function I use to set that? I couldnt find that function in the C reference file. 
My apologies if I overlooked anything, I am quite new to using DAQ boards.
Thank you again
HT