Scope this!

September 7, 2009 1:22 PM

I'm looking for affordable multimeter/scope software and USB compatible test probes for my Vista based laptop.

At work, I currently use a laptop for a lot of my automotive diagnosis. I have some hardware and software that turn my computer into a fantastic scan tool. A scan tool's best friend is a good multimeter. However, my multimeter doesn't have any scope or logging features. I also want to reduce the amount of gear that I have to drag back and forth to the car. The more I can run off my laptop, the better.
I've been Googling, and all the PC multimeter/scope software I've found is either expensive or requires a bulky adapter for the test leads.

Criteria:
Intutive interface for someone familiar with a scope.
It doesn't need to be too fancy. I just need to look at analog and digital signals and adjust the ms/division and volts/division until the trace looks good on my screen. An auto-range feature would be nice, too.
Compact, light-weight hardware or adapter. Test leads must be USB inputs. My laptop doesn't have a serial port.
Reasonably priced. I don't want to have to sell too much headlight fluid to pay for it ;)

Thanks everyone!

posted by Jon-o to technology (5 comments total)

Well, "reasonably priced" has varying definitions as you move from saying "multimeter" to saying "digital storage oscilloscope" :)

I've had some pretty good stuff from picotech; if you can live with 8 bit resolution, single-channel, 20MS/s, they offer a product that looks like a big pen with a USB cable coming out of it, and costs $210.

Their higher end products use normal oscilliscope probes to connect to the logging unit, which connects to the PC via USB. They take standard probes (so current clamps, attenuating probes etc are on offer) and they'll happily sell you a kit with probes, the logging unit, and some special automotive software if you've got $1600. For your money you get a faster sample rate, higher resolution, and multiple channels - if you need them.

I've got one of their older units which I've been fairly happy with - the downside is mine uses a parallel port connector and gets its power from a mains power supply which makes it a hassle to use on vehicles, especially moving ones! The newer ones use USB for data and power, which sounds like a lot less hassle. That said, if you go for the higher performance ones (which aren't pen-sized) you still have the data logging box to balance somewhere along with your laptop while you poke things with probes.

The software is pretty reasonable, albeit a bit odd in places. You can download a demo version, I think, to see what it's like.

I don't know if I've got $1600 worth of use out of mine, but I've certainly got $210 of use out of it :)
posted by Mike1024 at 2:25 PM on September 7 [1 favorite]

I know I've seen a few DAC cards that were PC Card. But keep in mind you'll always need some amount of interfacing between USB and the signal to be measured -- USB is 5V signalling and your car can go much much higher.
posted by pwnguin at 2:27 PM on September 7

I've been using the cheapest USB DAQ board from Measurement Computing for some other applications, though I've never fired up the o-scope software. If you don't need super-high sampling rate (I think you're limited to 1.2kSamples/sec) it would do the job fine, and it's only $129. It's also incredibly handy for quick motion control, robots, etc. if you like to tinker; the VB and VC++ libraries are excellent and work really well.
posted by range at 7:00 PM on September 7

Picotech looks right on the money with their offerings. I'm certainly not in the market for the $1600 package, but this looks about right.
Some decent resolution would be pretty important. Although most of my scope diagnosis involves intercepting a relatively low frequency hall-effect signal, duty cycle, or other digital pulse-width, I occasionally have to look at some pretty fast CAN bus networking signals, and some good resolution is really appreciated in that circumstance.
The glitch detecting feature on their software is exciting, too. I usually don't break out the scope until I'm trying to diagnose a really unusual and intermittent failure, when glitch detection would be really handy.

Thanks! I didn't know this good stuff was available. I was under the impression that this kind of technology was untouchable for less than a grand.
posted by Jon-o at 7:51 PM on September 7

If you want to look at CAN signals, you could just buy a USB CAN tool and go nuts. Even inject new data, but that seems like a recipe for failure given the whole systems assumptions one can build into CAN networking.
posted by pwnguin at 11:45 PM on September 7