First and foremost, the table below has a list of our Multifunction DAQ boards and their respective trigger resolution:
As you can see from the table, the trigger resolution on our DAQ boards is lower than the resolution of the analog inputs. This means that the voltages steps across the range are larger and you might see a larger difference between your trigger level and when the trigger is asserted. Even with reduced resolution, there are still some things that you can do to improve your results when using an analog trigger.
Unfortunately, the trigger circuit is not calibrated and you cannot pick trigger levels that fall on the resolution steps. The best you can do is account for the fact that the maximum voltage difference between your trigger level and level the trigger is actually asserted on is the range divided by 2^(trigger resolution).
To confirm the trigger resolution on your device, refer to the specifications document.