Re: CAN bus real-time sender and precise timestamp receiver tool

Hello David,

I think the same can be done as well with a two channel low cost PCI board,
e.g. SJA100 based, running can4linux.
Use the first CAN for transmission
and the second for receiving, time stamping and logging the traffic.

If you have control over the Linux OS, eg no streaming at eth0,
no extensive disk transfer, than reaching the 1 ms precision
is no problem.

Regards 
   Heinz   


Am Freitag, 11. September 2015, 13:28:18 schrieb Simon Byholm:
> Hello David
> 
> I usually do this with two CAN-USB interfaces. Because the timestamp
> is generated in the interface, not on the PC they are generally very
> good as long as you don't compare the timestamps of two different
> interface that have not been synced.
> 
> So you send on one interface, then you receive both the sent message
> and the answer from the tested device on the other CAN-USB interface.
> 
> That way both the sent message and the reply are timestamped on the
> same CAN-USB device, independent of the PC, so they are usually comparable
> with at least millisecond precision even on entry level CAN-USB interfaces.
> 
> This also removes the risk that the tx timestamp and rx timestamp may
> have different errors on entry level CAN-USB interfaces. Because you use
> the RX timestamp to record both the sent and received message if there's
> a fixed error, like from delays in the firmware of the CAN-USB device, these
> will have no impact on the measurment as both timestamps will have the
> same the same error.
> 
> The important thing is to make sure that your CAN-USB device generates the
> timestamp in the firmware, that it's not generated by your CAN analyzing
> software on the PC.
> 
> Simon
> 
> Simon Byholm - Software Manager / Quality Manager
> 
> Phone: +358 6 357 6306
> Fax: +358 6 357 6320
> email: [email protected]
> web: www.tke.fi
> 
> TK Engineering solves your CAN, CANopen, J1939 and NMEA2000 problems by providing the hardware, software and know-how you need to design, manufacture and troubleshoot your industrial and heavy machine CAN networks. Call +358 6 357 6300 or email [email protected] to learn how we can help you solve your CAN related problems.
> 
> On 11.9.2015 12:29, [email protected] wrote:
> > Hello
> >
> > For one of our equipment, we need to realize performance test over the CAN bus :
> >   - we want to send CAN messages at a frequency of 100Hz with a precision of 1ms to the equipment,
> >   - and also, to timestamp received CAN messages from the equipment at a precision of 1ms.
> >
> > We aren't able to do this with a "classic" USB-2-CAN interface because of the latency of the PC.
> >
> > Would you have any solution ?

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