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DAQmx triggering dataflow


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The last time I did data acquisition that required start triggering (ai/StartTrigger) was 5 years ago in a LV8.6 application.  I seem to remember that the dataflow would pause at the slave's DAQmx Start Task.vi until the master arrived at its DAQmx Start Task.vi, then each task would proceed to their DAQmx Read VIs.


Fast forward to LV2014 where I'm trying to help someone on another project get DAQmx start triggering working.   In LV2014, the process appears to operate differently and the slave's DAQmx Start Task.vi executes without pause and continues to the DAQmx Read.vi where it doesn't return data until the master AI input starts.


Did something change or am I growing old and developing dementia?

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Yes that is the way it works in DAQmx.  It makes sense that the task would start directly and then the acquiring of data into the buffer is inhibited until the trigger occurs.  I believe you can check the state of a task to determine if it is still waiting for a trigger or not.

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