Using Analog Channels To Trigger Acquisition on M or X Series Device

Updated Aug 8, 2018

Reported In

Software

  • LabVIEW Full

Driver

  • NI-DAQmx

Issue Details

I have an M or X Series DAQ card and I want to do analog edge triggering. Where can I find out which channels I can trigger off? Can I trigger off of any analog channel? What syntax do I use to trigger off a specific channel?
 

Solution

Not all M and X Series devices support analog triggering on all channels.  To determine what physical channels can be used as analog triggers, see the specifications document for your specific M Series or X Series device.  You can find the specifications document for your device by searching for your device model number at NI Product Manuals.
 
To use analog triggering, change the polymorphic selector on the DAQmx Start Trigger vi to 'Start Analog Edge', as shown in the snippet below:



Notice that by default the source terminal of the VI is a string data type instead of a DAQmx physical channel data type.  Consequently, you will have two options:
  1. Create a DAQmx physical channel constant or control and wire it into the source terminal to be coerced to a string, and select the physical channel to trigger off of from the dropdown menu.
  2. Type out the correct name for the specific physical channel that you would like to use into a string constant or control.

Additional Information

Note: To trigger off of an analog input, you must also be reading from that input. For instance, if you want to trigger off of Dev1/ai1, the task must be configured to read from Dev1/ai1 as well. If you do not, you will get Error -200265.



Note: If you are reading from multiple analog channels, you will need to make sure the channel you are triggering from is listed first. If you do not have the analog trigger source first, you will get Error -200131.


 

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