auto trigger USB-5132

[Andy Peters]

I have some USB-5132s that I am integrating into test fixtures that will be controlled by a LabView app. Basically, I need them to run in an auto-trigger mode, just like a standard digitizing 'scope. By this I mean that you set a trigger level and use edge triggering but in auto mode. In this case the 'scope continually retriggers, and when there's an actual trigger event, the display syncs up. So if you have the trigger position set at the center of the display, any edges that meet the trigger criterion line up in the center; otherwise the signal is displayed without regard to this kind of alignment.

The NI-SCOPE Soft Front Panel application can do this, so I know it's possible. But I can't sort out how to do this myself in LabView. One thought I had was to fake it: essentially set it up for normal edge triggering and if a timeout occurs, then simply use a software trigger to get new data and update the display. But I don't know how to set the trigger timeout.

Any ideas? Thanks.

[Andy Peters]

Replying to my own message ... I set up to trigger on an analog edge of appropriate level. niScope Read (poly).vi has a timeout parameter, which I set to something very short. The error out status of this sub VI drives the "?" input of a case statement. If true, we've timed out, so I abort the previous acquisition, set up an immediate trigger, call niScope Read (poly).vi again, and the output of this second niScope Read (poly).vi call drives my waveform display. If the first niScope Read (poly).vi does not time out, its wfm output drives my display.

Just in case anyone else wants to do this.

[Jennifer O]

Hi Andy,

Check out the "Configured Acquisition" example program that installs with the driver (help>>find examples).  Using the trigger modifier you can allow auto-triggering.  You can also query the auto-triggered property if you need to know if the acquired record was triggered or not.

- Jennifer O. 

[CWolf · Accepted solution]

Andy,

There is a property in NI-Scope that you can use to enable auto triggering.  The property is called Trigger Modifier, and it has two possible values: None (normal triggering) or Auto-Trigger.  There is also a property that is read-only called Auto-triggered, which will tell you whether an acquisition was auto-triggered or if an actual trigger was received. 

-Christina

[Andy Peters]

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CWolf wrote:

Andy,

There is a property in NI-Scope that you can use to enable auto triggering.  The property is called Trigger Modifier, and it has two possible values: None (normal triggering) or Auto-Trigger.  There is also a property that is read-only called Auto-triggered, which will tell you whether an acquisition was auto-triggered or if an actual trigger was received. 

-Christina

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Great, that's exactly what I need!

-a