Clues Needed

[steve ravet]

Bruce Plecan wrote:
> 
> Being new to the scope world, and after reading a scope manual, I'm still at
> a lose, and hope someone could clear these meanings up for me.
>   When using the triggering mode selection there are these options.
> Auto

It may mean that the scope triggers constantly, ie as soon as it
finishes drawing a trace it immediately draws another.  Or it may look
at the current signal and auto generate a level and slope trigger for
it.  Some HP scopes do that, in addition to setting the time base and
vertical scale automatically.

> + Internal
> - Internal

This setting means that the signal you are looking at generates a
trigger.  There should also be a level setting associated with these. 
The level is specified in volts.  When the signal that your probe is
connected is at that voltage then the scope triggers and generates a
waveform.  +/- sets the slope of the trigger.  If it's set to + the
scope triggers when the waveform rises through the trigger voltage.  If
it's -, it triggers as the voltage falls through the trigger voltage.

> +External
> -External

Probably means that there is a probe connection that can be used to
trigger the scope only.  +/- and level are same as for internal, but the
waveform on the external trigger can't be viewed.  You could, for
example, put the external trigger on the tach signal and use the other
channels to observe spark traces.

> Auto-seems to mean that the pulses are displayed as they occur, and the
> trigger
>   sense lead need not be connected.
> ALSO, for these 4 other options where would one hook the sense lead to.
> Any help here appreciated.
> Bruce
>      Happy used to, really chase the skirts.
>      But, having visited Scotland last weekend, has left him confused......

-- 
Steve Ravet
steve.ravet at arm.com
Advanced Risc Machines, Inc.
www.arm.com