how to read CAN - Page 1
Forum section: electronics / projects

author: subratri
author_rank: Contributor
timestamp: April 04, 2014, 08:01:34 am
content: Hi. First - sorry for my englishI have a problem with reading CAN bus in my car. I have been using CAN transceiver and then decoded it by signal analyzer. The problem is that i can record only 100ms. I have to say, im not fast enough to make a changesI sow same better analyzers but the prices are to hight. Cheapest one 150 euro. It is too much for me.I have one renault and CLIP sonda for it. Do any one know if there is a soft witch can uce the CLIP sonda to read fluently frames from CAN bus? Or maybe any cheap unit to read at list 2 min from the CAN ?THX for any help.PS. If this post is in wrong place pls move it

author: Rerouter
author_rank: Super Contributor
timestamp: April 04, 2014, 08:28:11 am
content: ELM327 to bluetooth adapter for $30 and a bit of software to talk and store over a standard serial interface (bluetooth is serial)

author: subratri
author_rank: Contributor
timestamp: April 04, 2014, 11:44:48 am
content: Yes, i know is many of the OBDII items, I think biger problem i have with soft... any idea what kind of? For Windows or even android... maybe im looking for it in wrong way or i have no luck at all...

author: ttp
author_rank: Regular Contributor
timestamp: April 05, 2014, 09:41:02 am
content: Quote from: subratri on April 04, 2014, 11:44:48 amI'm happy with Torque on Android, use on my phone and pad, it works with $10 bluetooth dongle from Ebay.http://torque-bhp.com/wikiThere is a free version but if you don't like it's limitations the full one is $4-5 from memory.

author: subratri
author_rank: Contributor
timestamp: April 05, 2014, 10:18:28 am
content: yes, but can u see the real frames ruing on the CAN bus? like full frames? ID Data CRC etc...? or only some useless information from ECU?

author: Niklas
author_rank: Frequent Contributor
timestamp: April 05, 2014, 04:48:27 pm
content: The identifier and 8 bytes of data is the are the interesting parts of the CAN message frame, not the CRC or header. Even if you can get a log of the CAN bus, do you have the relevant information about how to decode it?Some frames are sent periodically and some only on request or during special event. To maximize the use of bandwidth, the data is sometimes adjusted to use less bits before it is put in the frame. Why use 8 bits to represent the selected gear when 3 or 4 bits are enough? Offsets and scaling are also possible.The parameters that are sent, using the same identifier, can also be dependent on an index in the first or second byte. With extended identifier, i.e. 29 bits addressing space, you could waste a couple of identifiers and use the lower bits of them as index. With standard identifier and only 11 bits for addressing, then you must think different, making it more difficult to link specific data to a specific identifier.Unless you have the CAN database, with all this information about how to interpret the CAN log data, the data will probably give you next to nothing. The CAN database can also change between models and production years, even for the same manufacturer.

author: Macbeth
author_rank: Super Contributor
timestamp: April 05, 2014, 05:25:22 pm
content: Quote from: subratri on April 04, 2014, 08:01:34 amI would imagine you should be able to read the data packets using your Renault CAN CLiP "sonde" and the Dialogys/CLiP Windows software using a decent network packet analyzer such as Wireshark. I haven't used CLiP for over a year when I used it during fixing the aircon.What are you trying to achieve, may I ask? as a Renault Megane II, Ford Focus Mk I owner (and in possession of chinese clone Renault CLiP and Ford VCM adaptors)

author: subratri
author_rank: Contributor
timestamp: April 05, 2014, 08:38:39 pm
content: Quote from: Macbeth on April 05, 2014, 05:25:22 pmMaybe im not fluent enough in dialogsys but i can't find this option.Im looking for severals frames. For example i would like to have a turn lights using existing fog lights. I have build already an unit witch closing my roof remotely but i hardly want to be able to move the roof during driving. (megane CC) I can already do it but is not the way witch im looking for. So many ideas, many frames neededIm using my car as a labi have many years of brake with electronic. But Im getting fascinating againunfortunately most of my knowledge is already gone, but slowly recovering itBut... as it is only hobby (at list for now) i have to be very careful with money.

author: eurofox
author_rank: Unknown
timestamp: April 05, 2014, 11:11:37 pm
content: I would like to draw your attention that playing with the CAN write messages on a car could be risky.

author: subratri
author_rank: Contributor
timestamp: April 06, 2014, 08:20:28 am
content: live is risky.what about this one?http://www.microchipdirect.com/productsearch.aspx?keywords=APGDT002.Cheapest which i have find till now. Do someone know something about China clone or similar one?THX

author: subratri
author_rank: Contributor
timestamp: April 08, 2014, 06:57:01 am
content: Hi againdo someone know this unit?http://www.ebay.co.uk/itm/New-CANalyst-II-USB-to-CAN-Analyzer-CAN-BUS-Converter-Adapter-Support-ZLGCANpro-/281265022188?pt=UK_Computing_Parallel_Serial_PS_2&hash=item417cb3a4ecIt will be the cheapest existing one i thingis it worth buying it or better to get the Microchip one?