The conversation definitely
seems to have taken a bigger scope. Thank you for all the
discussions. I notice, there are 3 different points in the
1) Clarifying that Voff
applies even during power up and not only after power on has
- This was my original
intention. This doesn't change the existing standard behavior
at all – this only clarifies that Voff applies during power up
as well (as few of us have heard some customers arguing it
doesn't). Hence it will not make any compliant PD
2) Dead band between Von and
3) Does existing IEEE802.3 Std
2012 text indicate PD shall never turn off?
- Original IEEE802.3Std 2012
language of "The PD shall turn on at a voltage less than or equal to Von" -->
does this mean PD shall never turn PoE draw off if it has local
The original solution from me suggestion was only for 1).
The suggestion from Dan seems to cover 3) - but it becomes
slightly more complicated for 2). Given there is a language of
"less than or equal to" may be the original language of less
than or equal to Von suffices ?
Nevertheless, given we have a comment cycle coming up – face
to face discussions might help here. I will go ahead and submit
my original suggestion (only as a starter) which we can play
with more during comment resolution.
I think your point is good. A PD should not be mandated to
accept power once the PI voltage exceeds Von, but rather
it should be restricted from accepting power (beyond a
signature/class current) until the PI voltage exceeds Von.
How about this...
"The PD shall
not turn on until a voltage
greater than Voff and less than or equal to Von or
VPort_PD(min) whichever is
greater, is present at the PI."
This would allow PDs to draw local power or draw from
the LAN based on their own decision making process, but
would prevent them from drawing power until the PI
voltage meets the appropriate limits.
Nice hearing from you too. :)
On 3/17/15 10:55 AM, Michael
How does a PD ever turn off? In your
efforts to be able to affix blame for devices that are
non-compliant (trust me - idiots will still do idiotic
things you will only now have two things they fail to do
properly) you have precluded PDs which allow and
prioritize local power supplies.