Simon Clubley <clubley@remove_me.eisner.decus.org-earth.ufp> wrote:>
One interesting question however. I wonder if Scott is using RTS/CTS
for modem control or host-based flow control. There's a reason why CTS
was specified the way it is in the USB CDC ACM specifications even though
it's absolutely bloody useless for the normal case (at least these days)
of using those lines for host-based flow control.
Hmm, I see no mention of CTS in USB CDC ACM specification. To me this
means that vendor of USB serial convertor can implement is in essentially
any way. One sensible way is to handle it in the convertor, without
involving the USB host.
>
That's the point - the host has no knowledge of the flow control
situation due to the specification so it MUST be done in the USB
serial converter which I find to be very annoying personally as
it makes the behaviour vendor specific instead of being defined
by a standard. You also have the problem of telling the USB serial
converter to ignore the flow control (if you need to).
Simon.
--
Simon Clubley, clubley@remove_me.eisner.decus.org-Earth.UFP
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