Triggered AI Task Question

[Tony_Dean]

I would like to acquire data from multiple channels, started from an analogue trigger. The example program Acq-IntClk-AnlgStart is almost what I need but I have a question...

Once I have read the acquired data and read it using DAQmxReadAnalogF64, I would like to re-arm the trigger ready to acquire more data when the trigger conditions are met. I need to do this rcontinuously. What do I need to do to re-arm? Do I need to call DAQmxStopTask and/or DAQmxStartTask.

Thanks

Tony

[NIRebecca · Accepted solution]

Hey Tony, 

There are a couple of resources which I'm hoping will be of help. The following KnowledgeBase article outlines the process for configuring a retriggerable analog acquisition for X Series devices.

'How Can I Perform a Retriggerable Analog Acquisition' http://digital.ni.com/public.nsf/allkb/82DAECADE90CC56F8625659200675B2A

The section 'Application Architecture' in the following documentation provides additional context. 'Retriggerable Tasks in DAQmx' http://www.ni.com/tutorial/5382/en/

Below is some documentation pertaining to the DAQmx 'Retriggerable' property in C.
'Start >> More >> Retriggerable' http://zone.ni.com/reference/en-XX/help/370471AE-01/mxcprop/attr190f/

A few important observations to note:

1. The acquisition needs to be configured as 'Finite'. This means you will need to calculate the expected number of samples to be acquired in the 2.66 seconds between retriggering events. 
2. The Start >> More >> Retriggerable property should be set AFTER the trigger is configured.
3. If you want to acquire the digital data as well as trigger from it, you will need to split the signal source into a PFI line (for the trigger) and a DIO line (for the digital acquisition).

I hope this helps give you some direction to point your research in. 

All the best, 

Rebecca