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

Hi David;

My company makes a single channel USB CAN interface which timestamps 
receive messages with 1us resolution, and can optionally timestamp 
transmitted messages with the time they actually were sent out on the 
bus with 1us resolution.  That would allow you to use a single channel 
for this application.  If the USB latency is a major concern then our 
PCIe based cards have the same timestamping capabilities.
http://embeddedintelligence.com/

In my experience, you shouldn't have any problem transmitting from the 
PC with millisecond resolution.  Linux will likely give you the best 
results, but even under Windows it should be achievable.

I apologize for posting what may be deemed a commercial message on this 
list, but in this case it seemed relevant to the question posed.

Please feel free to contact me with any questions.

Steve Glow
President
Embedded Intelligence, Inc
508-380-0676

On 09/11/2015 06:28 AM, Simon Byholm wrote:
> 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 ?
>>
>> -- 
>> Archives and useful links: http://groups.yahoo.com/group/CANbus
>> Subscribe and unsubscribe at www.vector.com/canlist/
>> Report any problems to <[email protected]>
>>
>
> -- 
> Archives and useful links: http://groups.yahoo.com/group/CANbus
> Subscribe and unsubscribe at www.vector.com/canlist/
> Report any problems to <[email protected]>

--
Archives and useful links: http://groups.yahoo.com/group/CANbus
Subscribe and unsubscribe at www.vector.com/canlist/
Report any problems to <[email protected]>