I recently purchased a Rigol DHO814 digital scope and still learning how to use it. Compared to the analog scopes I used 30 years ago it seems to have a much larger selection of triggering conditions (and math functions). The sweep speed can go all the way down to (or is it up to?) 500 seconds/division. But, anything slower than 20msec/division the triggering is disabled. Pressing the Trigger button brings up an error message "Operation Disabled". Why?

I want to monitor a DC line after power up for 60-90 seconds. I want to set the scope to single sweep with positive edge triggering at about a 1vdc level.

Why can't I do this?

A work-around is to manually press the run/stop button to stop the sweep after 60 seconds. But, am I missing something?

 

At very low sweep rates it is difficult for the oscilloscope to trigger in Auto mode.

You need to set the Trigger to Manual and set the trigger level to an appropriate setting (usually half the trigger input voltage will do).

 

I don't see a manual trigger option (see picture).

 

For a minute I thought that the "Over" trigger condition might be what I was looking for. But, no. Once you set a sweep speed of 50msec/div or slower all trigger options and settings go away.

 

Sorry, I should have said Normal instead of Manual.
Select Normal instead of Auto on the top line.

 

For a minute I thought that the "Over" trigger condition might be what I was looking for. But, no. Once you set a sweep speed of 50msec/div or slower all trigger options and settings go away.

Have you read the manual? There are 40 pages on setting up the triggering, starting on page 61. If you don't have one, here is a copy of it:

User manual Rigol DHO814 (English - 253 pages)

 

Yes, I have the manual. I just found the setting I needed. It is to turn "ROLL" OFF instead of Auto. Now, the trigger settings do not go away (Invalid Operation) when I select a slow sweep speed. ROLL is halfway down the screen on the left side in the picture.