You can implement a start and stop trigger but not with an arbitrary number of points.
The 5112 has two triggers the Acquisition Arm and the Record Arm.
The Acquisition Arm trigger enables the Scope to start taking pretrigger data.
The Record arm trigger is often call the Stop trigger or Reference Trigger. Based upon the Reference Position the board will acquire X pretrigger samples and Y post trigger samples. The Reference trigger defines the transition from pre to post trigger. If you set all of your points to be pretrigger (i.e. 100% reference position) then the Reference trigger will stop acquistion on the trigger. One thing to note: the scope will not be ready to accept the record trigger until it has acquired all the pretrigger points. The scope
will only return one record size of data. Therefore the first samples will be lost.
For example I would like to start a acquisition with a trigger on PFI 1 and use edge triggering on channel 0 to stop the acquisition. I need at least 1000 points.
You will need to make the following changes in the code. Start from the niScope EX Configured Acquisition.vi and set up the triggering for Edge Trigger. Set your minimum record size to 1000 samples. On the diagram go to the Edge Trigger Case of the Triggering Selection Case Structure add a property node before the configure edge trigger similiar to the attached screen shot. Change the property to Acquisition Arm Source found in the synchronization menu. Change the property to write and create a string constant. The available sources for the Acq Arm are PFI 1,2 and RTSI 0-6. The syntax needs to match the following: "VAL_PFI_1". You will miss the edge trigger if you have not already acquired 1000 samples from the acquistion trigg
er and you will only get back 1000 samples.
Good luck and let me know if you have any questions.
Mike Taylor
