Micsig STO1104E: No Normal/Single Trigger slower than 100mS/division?

[IDEngineer]

I've been working on a different project using this scope and have discovered something interesting: It does not appear possible to do a single-trigger capture with a horizontal timebase setting slower than 100mS/division.

As an example, presume you have the scope set up with 1-2 probes and you're triggering on (say) channel 1. Everything works as expected if the timebase is set to 100mS/div or faster. But if I switch to 200mS/div or slower, two things happen:

1) The scope goes into auto trigger mode. It simply insists on self-triggering, even if the probes are disconnected.

2) Several trigger-related indicators disappear from the screen. This includes the trigger voltage level arrow on the right side, and the trigger position arrow and textual voltage indication at the top.

It's as if the entire trigger system is simply disabled at any horizontal speed slower than 100mS/div. Yes, in most cases with modern electronics that's not a huge issue, but on this project we have some signals that ramp over periods greater than a second and it is necessary to capture and review them. A storage scope is perfect for that, but not if it must be at least 100mS/div.

It just occurred to me while typing this that we might be able to configure the scope to capture a much longer/deeper sample despite the screen only showing 100mS/div. Perhaps that could work; capture first, then manually scroll around on the resulting memory. But it still begs the question of why the triggering system has this magic threshold at 100mS/div, slower than which you are not permitted to do single/normal trigger (it just switches into what appears to be "auto" mode).

I looked in the manual but didn't see anything about "slower than 100mS/div" in the horizontal nor trigger sections.

Any insight out there? Thanks!

EDIT: I figured a couple of screenshots would be helpful. The first image is 100mS/div, with triggering level (right side) and location (top side) visible. The second is what results after turning the Horizontal Scale knob one click, to 200mS/div, and no other changes. Note that the trigger indicators have disappeared. Pressing the Single button clears the trace but it is immediately triggered and proceeds from the right side of the screen.

[nctnico]

Look for 'roll mode'.

[electr_peter]

I think scope went into "roll mode" (from regular single/normal/auto mode) in slower timebase. Normal trigger mode produce counterintuitive* results at slow time bases so most scope manufacturers by default go to "roll mode" at slow time-bases. Micsig is no exception.

* normal trigger is very counterintuitive at slow time bases because at first scope shows a blank screen, then waits for some time to collect "pre-trigger data", then shows pre-trigger data on half of the screen and then updates with data after the trigger. It takes very long time, mostly shows a blank screen and destroys any data if you make a single adjustment to trigger, etc. Working principle is the same as with short time-bases, but in practice it is different. Normal triggering is useful when trigger event is rare and you have to wait for a long time, but generally roll mode is more user friendly.

[mikeselectricstuff]

There is a setting somewhere that tells it whether or not to go to roll mode at slower timebase speeds

[eurofox]

I just check on my Micsig with 5V pulse from 50 ms to 1 second time base without problem. 

[IDEngineer]

You guys nailed it - Roll Mode was enabled. Sorry for the amateur question!

Yep, Roll Mode would be most useful at slow sweep speeds. In fact, it would be nice if the GUI offered a configurable threshold... "roll mode is enabled >= xxxmS/div".

Thanks again!