Can anyone offer advice on how I determine the type of CAN network used on a vehicle?
As I understand there are several different types.....any suggestions or web-sites?
thanks
Jimmy
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Find a forum that specialises in the vehicle in question.
What vehicle? Someone may be able to suggest a forum.
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As regards CAN, there is one ISO standard with variants (i.e. high- low-speed CAN, basic- full-CAN etc). Do you actually mean CAN or do you really mean OBD-II diagnostic protocols (of which there are five)?
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Thanks for the replies, everyone.
Its actually on a New Holland tractor that's working in our area. The dealer boys were telling me one evening about it and how they had their own unique laptop in their dealership that was totally dedicated to the machine - esp. for new software, diagnosing faults etc. [trying to dazzle me with b/s, I thought]
Anyway curiosity got the better of me and I just got to thinking whether the tools we have for car C/B networks would work on there, surely they've only bought in a patent from someone like Bosch [or whoever] that specialise in it.
regards
James
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It is very likely that they do indeed have unique tools for that model. The CAN bus is simply a bus, a communication highway. Any manufacturer can plug whatever unique cpu's they want onto the bus.
A can bus is simply a network just like the internet. Abide by its network protocols and you can do anything you want with it. It is also used in satelites and many other non automotive applications.
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TourVanMan TM < Ex RF >
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Assuming you manage to get the correct tool / device to connect you to the BUS, you will be able to read everything that there is to be read. There will be lots of data wizzing about containing parameters, status information various flags, speeds, temperatures etc.
It would look something like this....
FFEEFFEE AB 0A CD 00 EE FF DD 1B 01411
FFEEFFEE AB 0A 00021
FFEEFFEE AB 0A CD 00 EE FF DD 1B 01411
FFEEFFEE AB 0A CD 00 EE FF DD 1B 01411
FFEEFFEE AB 0A CD 00 EE FF DD 1B 01411
FFEEFFEE AB 0A CD 00 EE FF DD 1B 01411
FFEEFFEE AB 0A CD 00 EE FF DD 1B 01411
A tool such as this (www.dgeinc.net/pdf/DGE CAN-Spy Datasheet.pdf ) will enable you to see what is going on.
The clever bit is the database that allows you to unstuff all of that garbage into information that is actually meaningful. That will tell you that enging speed, for example, is located on Message ID 4B0 and is shared across bytes 2 and 3. It is liikely that a factor and offset will also be applied. Basically, unless you know what you are looking at the infor is no use at all.
In addition to this may of the controller units (ECUs) connected to the bus will have the ability to store fault codes. This is the really useful bit but in order to cet a particular unit to release this information you have to be able to send a specific message to that unit. Its software will respond by reading some numbers from its memory and transmitting this info back over CAN (protocals are KWP2000, CCP etc.)
VMs have their own tools (eg: WDS within Ford), but general purpose tools are available (www.vector-informatik.com/vi_diagnostics_toolchain...m
l)
for doing this too. But you need the CAN database and lists of commands and responses. Once again, no use unless you are in the know. Software is expensive too!!
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