[etherlab-dev] Mailbox handling of interleaving responses

[Jeroen Van den Keybus]

Dear Gavin,


> I think a more robust solution would be to always scan for and fetch data
> out of the slave->master mailbox, and then queue these to the appropriate
> protocol-specific FSM to handle as they arrive, according to the type
> specified in the data itself (so that while FoE was waiting for a response
> it could successfully process a CoE or EoE response, for example).
>
>

> Does that make sense, or have I missed something?
>
>
I think it does. Incidentally, the Ethercat standard specifies to use the
Sync Manager (SM) write flag (SM offset 0x5 bit 0) for precisely that (or
try to read the buffer and observe the WKC).

But I also think that any protocol available in slaves (...oE) does not
post into the mailbox on its own initiative. Therefore, if the master does
not initiate any EoE, it should not fear encountering EoE traffic. Keeps
things simple, especially at the slave side.

To make matters more complicated, I have long lived in the belief that a
mailbox (sync manager) pair was needed per type of mailbox. The standard is
inconveniently unclear about that kind of details. But I found not a single
example of a multi-mailbox configuration.


J.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.etherlab.org/pipermail/etherlab-dev/attachments/20131119/fb025866/attachment.html>