Hey Quix,

I know, you already get this but maybe I can explain it more clearly.

The Modis/V-Pro trigger only works on a zoomed in screen.  If trigger is not met, the scope continues to acquire data in the buffer and only the screen will stop.  Then if you were to stop the scope and look at the capture, your triggered screen would vanish into oblivion if enough time has elapsed and that screen has scrolled out of the buffer.  You can't trigger the whole capture.

This prevents you from making use of trigger to capture a failure or other event.  There are not enough sample points on one screen to be of much use.

There is more detail on all this in this post we did a while back on an earlier Modis version.  Much of this still applies:

http://www.autonerdz.com/cgi/yabb2/YaBB.pl?num=1135299068/0

Pico has come a long way since then though with the PicoScope 6 developments and the ability to stream into the PC RAM at high speeds.  This allows Pico to pull way ahead of anything else out there right now, as far as raw sample rate power is concerned.

Quix,

I admire your thirst to learn.  You are sure in the right place.  We all have the same affliction.  Jut call us "Autonerdz Anonymous"   

What scope you are using doesn't matter nearly as much as understanding a bit about how it works and where your scope's limits are.  Almost any scope can be used effectively.  Where you get into trouble is working outside your scope's capability without realizing it.  All scopes have limits.  Some just more than others.

If you are interested in The Nerd Series on CD, you don't have to buy it all at once.  Just get Nerd I and I will send you the boxed set.  Then you can just purchase the keys for the other CDs when you are ready.

Glad you have been playing with the PicoScope software in demo.  That gives you a pretty good hands on experience.  What it cannot show is the high speed streaming capabilities.  You need the hardware for that.

You might also find the following post of interest.  This is an example of a modern throttle control system.  The capture shown cannot be duplicated by any other automotive scope today.  This capture is sampled 20x faster than a Modis.  The detail is astounding.

http://www.autonerdz.com/cgi/yabb2/YaBB.pl?num=1180471365

Qwix,

You will not be able to get that much information on the screen with the V-Pro. First of all, you're lacking two channels. And secondly, you don't have the resources. Having to run the scope zoomed in puts you at a disadvantage as well by not being able to see what is taking place. This how you have to run that scope to get any usable resolution. If you increase the timebase, you loose resolution and your sample rate, so you have to run it zoomed in.

I personally don't like running a scope in this manner. An event could happen with out you knowing it. The proponents will just say stop the scope and zoom out and review. Thats fine if you felt something, but what if you didn't? Would you know if an anomoly occured that the PCM recognized and you didn't? No. With those screens flying by at fast timebases, I have no idea. If there is more time on the screen, I would. Even if I got lucky, once I zoom out, the resolution is not on par with what I consider valuable real estate. I can take a paraded pattern with primary ignition coil current and pick out a problem with PicoScope and not do it with the Modis. It is like night and day. Trust me, I've tried.

As far as the Cobalt drive by wire operating at 10,000 Hz, you could grab two channels and see those. In order to see that digital frequency in the timebase shown and the slow analog TPS signal, you would have to operate at 10 mS and only then be able to recontruct that signal with 5 sample points. That is the minimum number needed. That is pushing it as hard as it will go, but it will do it. At 20 mS you are done. It is all about having enough sample points to reconstruct the waveform at longer timebases. The more the better.

I think where many get in to trouble is trying to put too much sweep speed on the screen with the V-Pro or the Modis. The key is to have the timebases small and then zoom out. It's a backwards zoom in a way. It works different. Much of what Tom already posted expains this. The main gripe I have with it is the horrible resolution. This is mainly because of the limited amount of pixels of the screen for display. You can indeed utilize the VGA port for an external monitor.  The hardware is 12 bit vertical resolution from what I understand. Since there is no zoom vertically, this is no advantage at this time, maybe for later. The Snap-on software needs some work in my opinion. The benchmark is already here and has been for some time.

Nerd 1 would be a good CD for you, Qwix. It goes in to great depth on the subject. Also, practice with your V-Pro as much as you can. Scope training classes are all over the place as far as quality. Be careful.  When you're ready for the advanced version, let us know. There is so much to learn. New tricks roll out daily.

Regards,

Carl

Thx for your input I find I get decent information at 1ms sweep, but I record it all and use a pc to view. I was able to pick out a bad crank sensor that way

I havent even played with the zoom out feature much, the small screen doesnt do it any justice

Mwebb Fortunately I have use of the V-Pro , the only one in the shop that does use a scope, so I dont have to buy it But I dont think I can talk the boss into a 4 channel, so the next purchase will have to be mine

Qwix

HI Tom and everybody in general 
My question is what do you think about the vetronix 5100 lab scope?  I have been looking for the specs so I can compared it using the calculator but haven't found them, I am asking you this because thats what we have at this time.