Author Topic: how much scope do I need  (Read 3261 times)

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Offline hotro1988

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how much scope do I need
« on: October 26, 2016, 09:43:24 am »
hello all, I am looking to get an oscilloscope and am hoping to get recommendations for automotive use. I've searched through the site, and many of the threads are a few years old and there have been a lot of advancements in oscilloscope technology. I am not an engineer and this is just a hobby, but I looking for something I can grow into. I would be using it for OBD 1 and early OBD2, eventually i would be working on more modern OBD 2 systems. Right now it would be easier systems like ignition control and communications with early OBD 2 control modules (body control module, PCM, ABS, etc..) I imagine eventually I will be looking at automotive can bus and the like. Would you recommend analog, digital, new or used. I am contemplating a Rigol DS1054Z but am not sure if 50Mhz will be enough for more modern systems such as can bus, or would I be better of with an older 2 channel analog scope in the 100-200 Mhz range. Thanks for any and all help.
 

Online tautech

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Re: how much scope do I need
« Reply #1 on: October 26, 2016, 09:55:42 am »
Don't know just where you are so I can't link the appropriate Siglent website.  :-//

A SDS1102X will do what you need for $ 424. The Decode package that includes CAN is included in a promotion ATM.
No need to hack it or anything like that, all you need is included in the price.
http://www.siglentamerica.com/pdxx.aspx?id=4688&T=2&tid=1
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Offline rob77

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Re: how much scope do I need
« Reply #2 on: October 26, 2016, 10:04:49 am »
what you mean by automotive use ? if you mean repairing cars, then you should really look after those specialized scopes optimized for such tasks like adjust ignition or inejctor timing....etc. something like the Hantek 1008C USB scope - it comes with various probes (HV for ignition, current probes for injectors...etc...) and it has 8 channels - enough even for american cars :) i'm not saying buy that Hantek... do your research and choose what fit your needs... but for car repairs definitely don't buy a lab scope.
 

Offline rstofer

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Re: how much scope do I need
« Reply #3 on: October 26, 2016, 10:42:44 am »
The process for unlocking 100 MHz on the DS1054Z is well understood.  Google for 'riglol', yes, misspelled. Search around the Test Equipment area as well.

You wind up with 100 MHz, full decoding options and a bunch of other options that make the DS1054Z pretty much the king of the entry level scopes at $400.  There is ALWAYS a discussion in the Test Equipment area here on EEVBlog.com.  Do be aware that most of the gripes have been corrected as of the latest firmware.  Also, some of the complaints are coming from folks making simple user errors.  It is far and away the most discussed scope.  I'm happy with mine!

A scope with equivalent features (after unlocking) by any other manufacturer will cost around $1200.

 

Offline ProBang2

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Re: how much scope do I need
« Reply #4 on: October 26, 2016, 11:57:44 am »

Calm down, folks. No need for a new Siglent vs. Rigol bashing. Both scopes are a wide overshot.
(We are talking about 1Mbit for the fast CAN and 125kbit for the slow CAN bus. OBD1/2 over VPM even slower.)

To check a cars electric (like spikes, analog sensor signals, PWM signals from sensors/to actuators, integrity of digital signals) is the mentioned 8 channel Hantek USB oscilloscope sufficient.

To get some meaningful data from the OBD is any DSO just useless (even if it is able to decode the CAN bus).

That is the task for an OBD reader. If there is anyway a laptop (hence the USB scope) in use, then it is possible to use a ELM- OBD- Interface, connected with the computer via USB or Bluetooth. For this solution are many programs available.
(Some as light versions even for free!)

Personaly I prefer a separate device as OBD reader. It should be able (at least) to:
- readout and decode DTC (Detected Trouble Code).
- show live data.
- show saved freeze frames.

More expensive ones give you access to e.g. the ABS.
Note: The additional modules have no common standard. Every car manufacturer has his own codes.

Professional tools including the software for all manufacturers plus wiring diagrams. For several thousend dollars...

Really full access to all modules is only possible with the specific diagnostic devices from the several car manufacturers.
They are not available for hobby use.

How much money do you want to spent?
How much functionality is needed?
Define "hobby use", please.
 



 
 

Offline rob77

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Re: how much scope do I need
« Reply #5 on: October 26, 2016, 08:11:32 pm »

Calm down, folks. No need for a new Siglent vs. Rigol bashing. Both scopes are a wide overshot.


overshot and not up to the task at the same time... a scope designed for a lab has no place in  car repair shop ;)

here is why:
- automotive scopes are coming with predefined pass-fail signal envelopes for testing ignition/injection/sensors.
- you need a set of different probes (current, HV , crocodile ...ect) those are not coming with lab scopes
- you need a battery powered scope - either stand alone or USB scope powered from the laptop's battery. it's highly impractical to have a extension cord flapping around...
- it must be small so you can let it sit on something in the engine compartment when measuring.
 

Offline JPortici

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Re: how much scope do I need
« Reply #6 on: October 26, 2016, 10:04:12 pm »
+1 on the scope is probably the wrong tool. decoding OBD is best done with other tools, also because you have to filter group and decode the data from the decoded can packet.
you can do it by hand but it is a very tedious and frustrating task. been there. Still, i encourage you to do so at some point if you plan to really learn and understand what the hell is going on when you throw a glance at a can bus, i was doing that while studying the related iso/sae literature and trying to figure out if understood what i was reading.

If you plan to develop hardware a scope is of course essential because the shape of the waveform matters a lot. you will have some requirements in bandwidth, risetime AND FUNCTIONALITY. even though scope X has enough BW it may lack other stuff like the ability to work with eye dyagrams masks (or some workaround to do so) and naturally protocol decoding, with can being one of the most popular.
Correct probes are maybe not necessary but very important too.
then at another point you will want to try your circuit in a car, as said having a scope with isolated ground is preferable. isolated channels would be cake but a tek tps is the cheapest you can have.. and it's not cheap. also it is very very very limited. This is when usb scopes come into play.
Like a picoscope (though possibly not the lowest end model). I suggest you don't get anything else as an usb scope, because of the functionality.
You can do automotive work with it (i do, at least.) without paying as much as they ask for a lecroy ws3k plus the required options.. or a keysight mso3kt plus the required options.
bandwidth? check.
memory? check.
then in the software (valid for all models)
eye dyagram + masks? check (or with workarounds)
can decoding? check.
lin decoding? check.
uwire, sent, flexray? check.
the possibility to acquire hundreds of MB of waveforms and having it all decoded and ready in a table? check.

but, but, but... again, all of this is unnecessary and useless if you don't pland to develop hardware. first things first, and obd scanner and decoder.
 

Offline george.b

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Re: how much scope do I need
« Reply #7 on: October 26, 2016, 10:38:02 pm »
Very scope, much wow.

An analog scope, as fond of squiggly green lines as I am, is out of the question for the uses you mention.
As others have already mentioned, a dedicated OBD tool would serve you much better for dealing with that. CAN is a slow bus and bandwidth/sampling rate don't really matter in this case for any remotely modern digital oscilloscope (i.e. just don't go throwing a sound card oscilloscope onto it).

Quote
Correct probes are maybe not necessary but very important too.
then at another point you will want to try your circuit in a car, as said having a scope with isolated ground is preferable. isolated channels would be cake but a tek tps is the cheapest you can have.. and it's not cheap.

Couldn't he make do with an isolation transformer?
 

Offline Gyro

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Re: how much scope do I need
« Reply #8 on: October 27, 2016, 02:23:02 am »
This is when usb scopes come into play.
Like a picoscope (though possibly not the lowest end model). I suggest you don't get anything else as an usb scope, because of the functionality.

Automotive diagnostics is actually one area where Picoscope have developed a strong niche market, with lots of specific tools an s/w. Check out their website.

https://www.picoauto.com/
« Last Edit: October 27, 2016, 02:24:39 am by Gyro »
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Offline Loboscope

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Re: how much scope do I need
« Reply #9 on: October 27, 2016, 07:19:06 am »
For car diagnostics via OBD etc. I can recommend "X431diag" [http://www.x431.com/website/index.do]. They sell hardware (OBD-Bluetooth-adapters) and software for any car manufacturer/car-model and it can readout failure code.
 

Offline hotro1988

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Re: how much scope do I need
« Reply #10 on: October 27, 2016, 03:43:12 pm »
Thanks for all the useful opinions everybody. yes I would be using it to help me diagnose problems for now. Factory tools are prohibitively expensive $5k for the tools alone, $3k per year to use their web based service to use the physical tool, also as far as I know manufactures do not publicly release protocol procedures. I am pretty sure what they do release you probably have to sign a non-disclosure to access the papers. Commercial tools are limited in what they can do; don't see too many that can read code outside of powertrain, ABS and SRS.  As far as future projects, I would like to integrate newer technology into older cars. I have a new 2016 GMC canyon but it has a lot of modules to deal with. It has a PCM, body control, human machine interface, integrated radio stack with touch screen, vehicle communications interface, transmission control module, etc.. Some of these modules are things I would eventually like to integrate especially the radio. Wrecking yards are a treasure trove of technology from all manufactures; this is why I was looking at buying a scope. When trying to integrate technology I know I will need to design my own hardware to make it function. Again, thanks for all the input.
 

Online tautech

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Re: how much scope do I need
« Reply #11 on: October 27, 2016, 06:19:48 pm »
Thanks for all the useful opinions everybody. yes I would be using it to help me diagnose problems for now. Factory tools are prohibitively expensive $5k for the tools alone, $3k per year to use their web based service to use the physical tool, also as far as I know manufactures do not publicly release protocol procedures. I am pretty sure what they do release you probably have to sign a non-disclosure to access the papers. Commercial tools are limited in what they can do; don't see too many that can read code outside of powertrain, ABS and SRS.  As far as future projects, I would like to integrate newer technology into older cars. I have a new 2016 GMC canyon but it has a lot of modules to deal with. It has a PCM, body control, human machine interface, integrated radio stack with touch screen, vehicle communications interface, transmission control module, etc.. Some of these modules are things I would eventually like to integrate especially the radio. Wrecking yards are a treasure trove of technology from all manufactures; this is why I was looking at buying a scope. When trying to integrate technology I know I will need to design my own hardware to make it function. Again, thanks for all the input.
Don't be too disillusioned by some of the comments, yes ODB is somewhat specialized but there are tools available in places like eBay.
I've successfully used a scope to diagnose a faulty ignition pack in a drag car so they're not entirely useless for auto work. In that case onboard logging of the EGT's pointed to an ignition fault when boost was at it's highest too, poor ignition energy was the logical suspect. Confirmed with a scope.  :P
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Offline kripton2035

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Re: how much scope do I need
« Reply #12 on: October 27, 2016, 06:36:46 pm »
The process for unlocking 100 MHz on the DS1054Z is well understood.  Google for 'riglol', yes, misspelled. Search around the Test Equipment area as well.

You wind up with 100 MHz, full decoding options and a bunch of other options that make the DS1054Z pretty much the king of the entry level scopes at $400.  There is ALWAYS a discussion in the Test Equipment area here on EEVBlog.com.  Do be aware that most of the gripes have been corrected as of the latest firmware.  Also, some of the complaints are coming from folks making simple user errors.  It is far and away the most discussed scope.  I'm happy with mine!

A scope with equivalent features (after unlocking) by any other manufacturer will cost around $1200.


I really like the rigol, but there is no CAN decode on the 1054z ...

Offline rstofer

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Re: how much scope do I need
« Reply #13 on: October 28, 2016, 01:16:29 am »
Don't be too disillusioned by some of the comments, yes ODB is somewhat specialized but there are tools available in places like eBay.
I've successfully used a scope to diagnose a faulty ignition pack in a drag car so they're not entirely useless for auto work. In that case onboard logging of the EGT's pointed to an ignition fault when boost was at it's highest too, poor ignition energy was the logical suspect. Confirmed with a scope.  :P

Way back in the '60s, I had a Heathkit Ignition Scope that I used to keep track of the ignition systems on our drag cars.  Nice tool!

i'm pretty sure with some form of inductive pickup, I could do the same kind of thing with any other scope but it would take a little effort.  Maybe the pickup off a decent timing light could be used.  The result would be nowhere near as specialized or as easy to use for the purpose.
 

Online tautech

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Re: how much scope do I need
« Reply #14 on: October 28, 2016, 05:03:50 am »
Don't be too disillusioned by some of the comments, yes ODB is somewhat specialized but there are tools available in places like eBay.
I've successfully used a scope to diagnose a faulty ignition pack in a drag car so they're not entirely useless for auto work. In that case onboard logging of the EGT's pointed to an ignition fault when boost was at it's highest too, poor ignition energy was the logical suspect. Confirmed with a scope.  :P

Way back in the '60s, I had a Heathkit Ignition Scope that I used to keep track of the ignition systems on our drag cars.  Nice tool!

i'm pretty sure with some form of inductive pickup, I could do the same kind of thing with any other scope but it would take a little effort.  Maybe the pickup off a decent timing light could be used.  The result would be nowhere near as specialized or as easy to use for the purpose.
Things are done a bit different these days.
ECU> Ignition pack> Coils.
There's no need to probe spark plug voltages.  :scared:
3-400V pulses can be examined with 10:1 probes, especially at the low frequencies that auto ignitions work at.
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