Re: more X-rays Silvertel PoE Supply

On 10/2/2024 11:02 AM, Edward Rawde wrote:

"Don Y" <blockedofcourse@foo.invalid> wrote in message news:vdjvmh$3aipj$1@dont-email.me...

On 10/2/2024 8:46 AM, Edward Rawde wrote:

I did PoE with LTC4267 some years ago such that 12V could also be supplied from a wart.
Fully isolated with a PA1138 transformer.

>
How did you inform the PD of the fact that it was no longer
dependant on (and controllable by) the PSE?  Or, did you forego
in-band reconfiguration and power control?

 It wasn't necessary for the fairly specialized product which was configured at install time with power from PoE or wart but not
both.
I seem to recall at least one accidental connection of both with no detrimental effect but it wasn't investigated further.

One of the benefits of PoE (IMHO) is that it allows the PD to
be power cycled, remotely (instead of forcing the user to
power the device off and.or disconnect it from the network).
In-band power control also lets it renegotiate its operating
class.  E.g., I often downgrade devices to Class 1 if the I/Os
aren't strictly necessary.  And, "off" with just a little
power to keep the PoE interface "operational" so it can
pretend to be "replugged" (without having to truly unplug
and replug to reinitiate the power negotiation.
If the device *thinks* it is going to be powered off -- and
brings itself to a "safe" state before the PSE removes
power -- but then finds itself still powered *on* (even though
the PSE has dropped the load) things can get confusing...
should I now *assume* I'm a class 3 device?  Or, higher??
(after all, with local power, I can pretend I am PoE+!)