[etherlab-users] Reference clocks and empty configurations

[Gavin Lambert]

Yesterday, I wrote:
> I've recently been trying to test a bunch of unusual configurations to
> see how things behave.  One of these is a configuration where slaves are
> present on the network, but none have been added to any domains.  (It
> seems like a reasonable interim bring-up state.)
> 
> In this case, if I call ecrt_master_activate and run a realtime loop
> (dispatching internal packets but not actually processing any domains)
> then the first slave on the network will log a "Sync manager watchdog"
> error frequently (about twice per second, at least with my test setup),
> because the master keeps putting it into OP but is not actually sending
> any output data to it.
[...]
> 3. Why does it want to have a reference clock at all in a network with
> no configured slaves, even when slaves are present?

4. Assuming the slave permits it, if the master does want a non-configured
slave to go to OP for some reason, shouldn't it at least do minimal
configuration such as clearing its PDO Assign registers first (so the SMs
are empty), and/or disabling the SM watchdog?

(Although clearing the Assign registers means "ethercat pdos" etc would lose
the ability to see the slave's PDOs until rebooted or manually reconfigured,
due to the issue I mentioned last month.)