[etherlab-users] Theoretical DC question.

Raz Ben Yehuda rbenyehuda at manz.com
Mon Jul 23 11:37:12 CEST 2012

On Mon, 2012-07-23 at 09:12 +0200, Richard Hacker wrote:
> On Sunday 22 July 2012 12:31:41 Raz Ben Yehuda wrote:
> > How do we make the master transmit packet in the right time ?
> No, you don't tell the master to transmit the packet at the right time, you 
> must just tell the master deterministically what the time is. 
> Deterministically means, do not spend variable periods of time between telling 
> the master the current time (ecrt_master_application_time()) and calling it 
> (ecrt_master_sync_slave_clocks() and ecrt_master_send())
> > 
Ok, given am NOT spending variable time taking the current time and
transmitting. I do not see how Etherlab conform to Beckhoff requirement
that a "Frame has to be received before sync0 Event is generated" ? 

Is it the application responsibility or not to consider the propagation
time ?

Thank you 

> > Is is said in the etherlab book that all slaves are fixing the local
> > clocks according to a caluclated error.
> > 1. who writes to the system time register ? is it the first slave or the
> > master ? I noticed that it possible to that in the master but this is
> > not the correct behavior as i understand.
> > 
> > 2. if a master needs to transmit the N-th packet so that i will be
> > processed in the N-th tick of the reference (first) slave, how do i do
> > that ? how do i know how much time BEFORE the n-th tick to transmit the
> > packet ?
> > 
> > thank you
> > 
> Mit freundlichem Gruß
> Richard Hacker


More information about the Etherlab-users mailing list