Analog 'scopes have a function which was commonly referred to as "free running", where the sweep is running continuously, not needing triggering from any input signal.
Just AUTO trigger on a DSO ?
When probing mostly DC voltages such as around a logic IC, AUTO trigger keeps starting and stopping, ....so I sometimes switch the trigger to AC line, which gives a permanent trace, which you see flicking up to 5V - or not, without taking your eyes off the IC pins/probe.
Would it be better with a faster time /div setting in AUTO? (that's also what they call it on analog 'scopes)
I didn't bring up the term AUTO because of possible confusion with the AUTOSET button on DSOs.
I think there was a discussion on this forum about AUTO trigger.
From memory, the repetition rate of drawing the line on a DSO in that mode doesn't directly follow the time/div setting, (It is quite a bit slower, whereas with an analog instrument it is a little bit faster), but it does change with the setting of that control.
These are two different things.
Automatic versus single sweep or normal just means that the sweep is triggered automatically after a timeout if no trigger event is detected. This is what creates the pause in updating the display.
Automatic also may refer to how the trigger level is updated. In the event of loss of triggering, automatic level sets the trigger level to 50% of the peak-to-peak value. Unfortunately this interacts with the automatic triggering above to continuously interrupt the sweeps. Automatic peak-to-peak level is something else entirely where the trigger level is updated continuously without interrupting the sweeps and is much faster but offhand I do not know of any modern DSOs which support this.
Usually the two separate configurations above are combined but they are separate on some oscilloscopes or at least on some older oscilloscopes. You might for instance want automatic sweeps without automatic level for a continuous sweep without annoying pauses.
As far a the original question, I would probably start off using automatic mode with the trigger configured to continuous sweep if possible at a low time/div, say 1ms/div, and with persistence set to a longer duration just to get an idea about what is going on.
Then the sweep can be set to normal and the trigger adjusted to view a specific event if there is one.