$30 OBD2 CAN tool

[tboult]

Summary: help me pick a $50 present for myself.

I was very excited back in October when these OBD2 threads started popping up -- besides this one, there's a couple on the DashDAQ. Initially I was going to go ahead and get a DashDAQ, but that's a steep price and in the last couple months I've had to reign in my cash flow a bit. So I put that whole thing on pause.

I took a look at this thread, which apparently enables a poor-man's view of the OBD2 data, but I decided I didn't have time to even do that.

Well, now a family member has asked me for a $50 gift idea for myself, and I've already given out all my other ideas (books etc.). So I figured I might as well get one of these cheap OBD2 readers and have a little fun with it, even if it doesn't give me the Volt-specific parameters like MGA/MGB torque, battery points, etc.

The "ElmScan 5" mentioned in the first post in this thread doesn't seem to be available anymore. In its place there is the "OBDLink SX" scan tool, which terminates in a USB connector so I guess is intended for laptop use. I'd prefer Bluetooth and Android compatibility so I can idly fiddle with it on my cell phone without cable hassle.

Can you all recommend a $50 product for reading OBD2 data, even if it doesn't give you the Volt stuff? If it requires a Windows laptop for reading then I'll live, but interfacing to an Android app would be awesome. If USB only then I can get the necessary cable, but if it can do Bluetooth then that's even better.

I've been using
http://www.ebay.com/itm/Mini-ELM327-...ht_4464wt_1187
and torque. Still not getting any volt specific (searching for PIDs is a slow process and I'm overworked and my wife thinks I'm spending too time on th volt as it is.) However I'm not having any problem in talking to the vtech via the phone, so to me its a software issue. The torque developer said he may provide Monitor All in the plugin support, though if it gets to be xmax break and nothing happens I may develop my own low level stuff from scratch. (there are various open-source OBDb low-level tools (most are GPL, but I'm okay with a GPL release of what I learn about the volt). If I build on torque there are lots of stuff worth the $5 app fee, (lots of nice graphics and other stuff) so I'm hoping Ian will add what I need.

[RScott]

Summary: help me pick a $50 present for myself.

It sounds like ScanTool pulled a fast one -- deciding to discontinue the ElmScan 5, selling it cheap on Amazon ($30) to get rid of excess stock, and only then announcing that it is being discontinued. I had assumed that $30 was their normal discounted price on Amazon, but it now appears in their "discontinued" section. If anyone is looking to buy one, now is the time to do so while it is showing as available on Amazon.

The main drawback I found to the Elmscan 5 is that it was limited to a 500kbps connection to the computer, which caused data to sometimes get lost. In most cases, it isn't a big deal (as much of the data is transmitted often enough that losing some isn't a problem). But you never know if something useful might get lost. I'm not sure of the OBDLink SX offers a faster connection; their site doesn't mention it. Their claim of a large buffer should get around the problem even at 500kbps, though (the Elmscan 5 has a 256 byte buffer).

Something else to be aware of is that there are some cheap no-name OBD2 readers out there that use counterfeit ELM chips. And some may not support speeds high enough to be worthwhile (if you're thinking of using the "monitor all" mode, 500kbps should be the minimum considered; the ElmScan 5 and presumably the OBDLink SX do 500kbps).

[ChrisC]

The OBDLink SX is right in my target price range ($50) so if that's a decent one that I'll run with that. Just looking for some confirmation. Thanks!

So, it's Christmas Day and I did indeed get an OBDLink SX. I just now installed the software on a laptop and tested it out with my Volt and it connects up OK and read some values, so I know that the basic setup is good.

Next I'll dig into this thread and see what kinds of things I can look at (and which ECUs to talk to). If anyone wants to give me some initial guidance, I'm all ears! I'm aware that I won't be able to read a lot of the Volt-specific things. It's a start.

Merry Christmas!

[markwj]

As I sift through all the data, I've found that I need to take more and more notes on everything.

I'm starting a page at http://www.EVtools.info/ChevyVoltOBD2CAN.html that covers what I've discovered so far (I'd simply post here, but would need to keep editing posts all the time).

I head up the open vehicles project (www.openvehicles.com) - a smartphone app, server and car module to allow remote monitoring and control of EVs. Our first supported vehicle was the Tesla Roadster, and we've had a lot of enquiries from European users (who are just now getting Volt/Amperas and don't have OnStar for remote cellular access) about OVMS for their Amperas.

It seems we have a lot of similarity between our projects, particular regarding CAN hacking. Thanks for publishing these notes. They are an excellent start with this.

We've got some developers in Germany starting to work on their Amperas - trying to get SOC, GPS Location, Speed, etc, off the CAN bus then on to the OVMS servers for display in smartphone apps.

No specific questions / feedback at the moment, but I'm hoping we can co-operate on this. With the Tesla Roadster, we had four guys working on decoding the can bus and have made excellent progress (decoding almost the entire bus, and 99% of the important stuff). Perhaps something similar to Volt/Ampera can have similar results.

[RScott]

I head up the open vehicles project (www.openvehicles.com) - a smartphone app, server and car module to allow remote monitoring and control of EVs.
...
No specific questions / feedback at the moment, but I'm hoping we can co-operate on this. With the Tesla Roadster, we had four guys working on decoding the can bus and have made excellent progress (decoding almost the entire bus, and 99% of the important stuff). Perhaps something similar to Volt/Ampera can have similar results.

That is something I'm sure a lot of Volt/Ampera owners would *love*.

If you aren't yet aware, OnStar claimed about 5 months ago that they were releasing an API for developers, but they never contacted those that were interested since then (including the person that runs www.voltstats.net, who fortunately got access to an early now-confidential API). But, I believe some people have simply written scripts to log in and download the data as if they were a user accessing the site.

The Volt gets pretty complex (e.g. it has several different OBD2 buses, only one of which I have been able to access, so there may be a lot of data that is harder to access), but fortunately there is a lot of useful data that is easy to access.

All of the data that I have been accessing is through the CAN "monitor all" mode (which listens to whatever the car is sending), rather than sending specific requests (as most OBD2 applications do). The nice thing about that is that all the data is just sitting there waiting to be interpreted (and can easily be logged, even if you have no idea what it is yet). My focus has been on collecting data that can later be analyzed (one of the first ideas being to check two different routes to see which uses less electricity).

I hope to start a new thread soon with the program that I am using to collect the data, so that Volt/Ampera owners who are interested can start collecting data from their cars, either to help decode the CAN data or to save the data for future analysis.

[markwj]

If you aren't yet aware, OnStar claimed about 5 months ago that they were releasing an API for developers, but they never contacted those that were interested since then (including the person that runs www.voltstats.net, who fortunately got access to an early now-confidential API). But, I believe some people have simply written scripts to log in and download the data as if they were a user accessing the site.

With the help of an owner I tried that as an investigation into seeing how hard it would be to 'gateway' US Volts into OVMS. But, not good. The first problem is the api - as you point out it is not really 'published' and little response from GM. The second problem is the architecture itself is similar to the Leaf carvings. The car is not permanently connected, but instead receives a 'wakeup' message from the central servers, at which time it wakes up, transmits its status, then goes offline again.

OVMS works differently. With OVMS, the car connects back to the server and maintains that connection open (using very little data - just a small keep alive once every few minutes, and periodic status updates). If an App connects, the car is immediately informed and immediately starts reporting realtime status. The response to an App connecting is usually 1 to 3 seconds (including all the round-trip times), vs a common 30 to 60 seconds for the Leaf or Onstar systems. But, the key point is that with this always on connection and the ability for the server to talk to the car anytime it wants, we can offload a lot of the work to the server and apps.

The other point is that the amount of information available to owners is a tiny fraction of what is available on the car buses. The manufacturers give the users what the manufacturers want (case in point the recent cripleware update to dashdaq). OVMS is trying to give the users what they want.

We haven't given up the idea of a 'gateway' to the Leaf Carwings and Volt Onstar, but will probably wait for official APIs.

All of the data that I have been accessing is through the CAN "monitor all" mode (which listens to whatever the car is sending), rather than sending specific requests (as most OBD2 applications do). The nice thing about that is that all the data is just sitting there waiting to be interpreted (and can easily be logged, even if you have no idea what it is yet).

Yep, that's exactly what we do with the Tesla Roadster. Works very well. You can also configure the unit to be CAN-bus passive in 'listen' mode, which will have very limited impact on the car.

I hope to start a new thread soon with the program that I am using to collect the data, so that Volt/Ampera owners who are interested can start collecting data from their cars, either to help decode the CAN data or to save the data for future analysis.

You've made an amazing start on the decode. We'll share what we find here and on a master document we'll maintain on our github repository, and encourage you and others to do the same.

Regards, Mark.