Oh and here's a link to a logic analyzer screen shot of CANbus Arbitration.  
The two bottom modules  are both trying to send at the same time.  The top 
module just receives and at the end of the message inserts the ACK bit.  The 
two bottom pairs arbitrate with the bottom module releasing the bus, receiving 
the message and also sending the ACK bit and then retrying the transmission.

Classic CAN.


It's not a really fast bit rate because it was done with my CANRF hardware 
which used ON OFF KEYING (OOK) at 916.5MHz to send wireless CAN.  That project 
was scrapped after ZigBee came out.

John Dammeyer

> -----Original Message-----
> From: Nicklas Karlsson [mailto:nicklas.karlsso...@gmail.com]
> Sent: March-09-19 8:37 AM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] CANopen: SOEM/SOES, CANfestival, anything
> more?
> > ...
> > For more hard real time applications the MilCAN protocol is more ideal
> because all the messages are synchronized to SYNC FLAG messages and the
> arbitration is limited to within a SYNC FLAG period avoiding jitter on
> messages.  But there's pretty well nothing available commercially for
> MilCAN unfortunately.
> CANopen have a SYNC message, this is not as good as SYNC FLAG?
> >
> > Where CAN bus systems really excel in automation is for things like tool
> changers and part loaders/unloaders, control of coolant and other devices
> etc.
> Sound reasonable. I plan to use it over Ethercat, its just to get some kind of
> standarized message for configuration or whenever there is a need to
> communicate with the device.
> > Still one of the best books on CANopen is this one.  Looks like it's back in
> print too.  I've used it to create a master CANopen Stack.
> > https://www.canopenbook.com/
> Nice picture, I will try to look at it.
> Regards Nicklas Karlsson
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