On 28.01.2011 11:44, Kurt Van Dijck wrote:
> From j1939 point of view, there is no 'box', but only a collection of ECU's.
> Reordering the collection of ECU's is allowed.
>>
>> An example:
>>
>> I implement a vehicle diagnosis application called 'mydiag' that communicates
>> with a CAN ECU (e.g. an instrument cluster) using the ISO 15765-2 transport
>> protocol sockets.
>>
>> Then i can do a real diag session like this:
>>
>> mydiag -s 123 -d 321 can0
>>
>> assuming the instrument cluster ECU is connected to can0 and the CAN IDs 123
>> and 321 are used for the ISO-TP transport protocol channel.
>>
>> And now i write a simulation for the instrument cluster ECU called
>> 'myecusim'.
>>
>> From now, i can simulate, test and develop the diagnosis application with the
>> ECU simulation on my Linux host without any real hardware:
>>
>> Start simulation
>>
>> myecusim -s 321 -d 123 vcan0 &
>>
>> Start diagnosis application
>>
>> mydiag -s 123 -d 321 vcan0
>>
>> Finally i can simulate e.g. 30 different ECUs at the same time on my Linux
>> host to test and develop my diagnosis application (on a business trip without
>> hardware!).
>>
>> If you attach the source address SA to the CAN interface, this means that you
>> Linux host can only act as ONE ECU, right?
>>
> Now we're getting somewhere.
:-)
> in my j1939 view:
>
> regular setup:
> $ ip addr add j1939 0x80 dev can0
> $ mydiag --dev can0 --sa 0x80 --da 0x81
>
> and simulated:
> $ ip addr add j1939 0x80 dev vcan0
> $ ip addr add j1939 0x81 dev vcan0
> $ myecusim --dev vcan0 --sa 0x81
> $ mydiag --dev vcan0 --sa 0x80 --da 0x81
>
>>
>> And if you put multiple SAs on the network interface, how could it be made
>> clear for the different processes / applications on the host, on which SA
>> they
>> are working??
> struct sockaddr_can saddr;
>
> saddr.can_ifindex = ifindex("vcan0");
> saddr.can_addr.j1939.sa = 0x80;
> bind(sock, &saddr, ...);
>>
>> Got the problem?
> I hope I explained the answer well?
See my question below ...
> This example did not show the full power of SA bound to interfaces, since
> only 1 application per ECU was run.
>
> Within J1939, and that I think is the major difference, the CAN id is split
> in a SA & PGN. 2 apps can/may/must use the same SA, with different PGN.
> I could so run:
>
> $ mydiag --dev can0 --sa 0x80 --da 0x81 &
> $ mydiag --dev can0 --sa 0x80 --da 0x82 &
Why is the SA bound to the netdevice needed, if you set all the addresses by
commandline here?
> $ mydiag2 --dev can0 --sa 0x80 &
and here?
> $ mytimestampbroadcast --dev can0 &
ok - here you left out the '--sa <addr>' as you have set a default on the
netdevice, right?
But what address is used here as SA? 0x80 or 0x81 (both set by 'ip addr add'
above)?
Regards,
Oliver
> ....
> as well.
> I plain CAN, each of the above applications _need_ diffenent CAN-id,
> in J1939, the SA is reused within an ECU.
> An ECU is then defined be a collection of applications reusing the same
> SA.
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