Re: ISOTP-implementation

[Oliver Hartkopp <socketcan@hartkopp.net>]

On 02.10.2012 10:33, Mahesh Maharjan wrote:

> 
> Thank you Oliver providing me some guideline to use  ISO-TP socketCan for multiple socket. 
> In my previous queries- I think, I could not able to describe my problem properly.
> While working with RAW socket in Imx6, I was having problem with frame lost during the Tx. So, I was thinking to use multiple socket to minimise the lost of can frame in ISOTP also. 


Can you be a bit more detailed please?

Frames usually do not get lost - unless the driver is faulty OR you did not
check the return values for the raw socket you've been using ??

> 
> Another important things about Point to Point(ISOTP), as you wrote me;
> One write() syscall -> one ISO-TP PDU is sent
> 
> One ISO-TP PDU is received -> one read() syscall get's the PDU
> 
> Would you please provide some further guide line on it, whether I can use some acknowledge between read Or writing frames. So I would prefer to know get inform with complete  tranmsmission Complete or  Received Complete...


ISO-TP is an unreliable datagramm protocol, like UDP/IP.

The PDU loss has therefore to be detected by a higher layer. E.g. the UDS
diagnosis service has it's own timeout for application message timeouts.

So send a ISO-TP PDU, assume it gone ok and wait for an application layer
answer (with timeout).

Did you follow this hint?
https://gitorious.org/linux-can/can-modules/blobs/master/README.isotp#line212

Regards,
Oliver