RE: detecting a PD disconnection event
Yair, et al, wrt published papers the 802.5 LAN, as mentioned by Bob Love
yesterday,
is a good starting point as it uses precisly this method (cessation of sense
current) to
identify removal of a piece of LAN equipment, and take an action (circuit / port
by-pass
in a MAU). Note any such papers should precede dec 92 for legal reasons .....
my preference is still for option 1a. I can see it might be wise to have a
backup, but don't
much like any of the alternatives suggested, one thought I had that might help
1a, is:
ensure that the PSE state machine & Power source takes no action on
current < threshold other than to let the current turn off, and the discovery
process begin
again (ie no alarms, no status reporting, no registers / MIBS - nothing other
than returning
to the discovery state). Obviously the status of the PSE state machine can be
reported,
but you cannot infer directly from this without refference to previous states
etc that a
piece of equipment has been removed. Other silly ideas: Allow the PD to have an
on / off switch which disconnects the PD's PSU (removes any explicit association
between cessation of current draw, and device removal).
regards , Nick
see you at the Bar ......
Yair Darshan <YairD@xxxxxxxxxxxxxx> on 29/04/2001 01:16:16
Sent by: Yair Darshan <YairD@xxxxxxxxxxxxxx>
To: "'Bachand, Jerry'" <gbachand@xxxxxxxxx>, "'Rick Brooks'"
<ribrooks@xxxxxxxxxxxxxxxxxx>, Barry Male <male@xxxxxxxxxxxxxxxxxxxxxx>
cc: stds-802-3-pwrviamdi@xxxxxxxx, Nehemia Schwartz <NehemiaS@xxxxxxxxxxxxxx>
(Nick Stapleton/GB/3Com)
Subject: RE: detecting a PD disconnection event
Jerry,
I agree with you it is very basic and I am also supporting 1a, It was our
favorite option. However, in order to be covered legally we need to find a
paper that publicly distributed and demonstrating this concept.
Does any body has such publication?
Yair.
> -----Original Message-----
> From: Bachand, Jerry [SMTP:gbachand@xxxxxxxxx]
> Sent: ו, אפריל 27, 2001 9:07 PM
> To: 'Rick Brooks'; Barry Male
> Cc: stds-802-3-pwrviamdi@xxxxxxxx
> Subject: RE: detecting a PD disconnection event
>
>
> Rick and group,
>
> I still prefer 1a.
> Since detecting a minimum current is such a basic and obvious means to
> detect a disconnect, I don't think anyone could even think of suing. (Not
> even Lucent or Avaya.) ;-)
>
> This means of detecting a disconnect has been in use for over 100yrs by
> telephone companies, worldwide, to detect the telephone on-hook condition.
>
> However, I have no problem with other means, as you mentioned, as long as
> the minimum current method can still be used.
>
> Please keep in mind, eventually there will be many other devices powered
> by
> the Ethernet, simple might give us more flexibility in the future.
>
> Regards
>
> Jerry
>
>
>
>
> Gerard E. (Jerry) Bachand
> Avaya Inc.
> 300 Baker Avenue, Suite 100
> Concord, MA 01742
>
> (978) 318-6402 Voice
> (978) 318-6402 Fax
>
> <gbachand@xxxxxxxxx>
>
> Formerly: Enterprise Networks Group
> ("Cajun" LAN Systems)
> of Lucent Technologies
>
>
>
>
> -----Original Message-----
> From: Rick Brooks [mailto:ribrooks@xxxxxxxxxxxxxxxxxx]
> Sent: Friday, April 27, 2001 1:40 PM
> To: Barry Male
> Cc: stds-802-3-pwrviamdi@xxxxxxxx
> Subject: RE: detecting a PD disconnection event
>
>
>
> Barry,
> 1a) was all of our favorites until Geoff's recent email regarding a patent
> issue.
>
> It may turn out that other methods are more cost effective when considered
> globally.
> My proposal is that more than one method could be used, not just the one
> that we have been assuming.
> My view is that we must at least consider alternative methods that do not
> use DC current sensing.
>
> thanks,
> - Rick
>
>
>
>
> -----Original Message-----
> From: Barry Male [SMTP:male@xxxxxxxxxxxxxxxxxxxxxx]
> Sent: Friday, April 27, 2001 10:29 AM
> To: Brooks, Rick [SC5:321:EXCH]
> Cc: stds-802-3-pwrviamdi@xxxxxxxx
> Subject: Re: detecting a PD disconnection event
>
>
> Rick,
>
> My preference is 1a.
>
> Have the PSE disconnect if the AVERAGE value of load current is less
> than
> 10mA for a sample period of some time (say 100mSec)
>
> This averaging produces a robust detection method from the
> standpoint of
> system noise.
>
> Thanks
>
> Barry
>
> _________________________________________________________________
> Barry Male
> Senior Principal IC Designer Internet: barry_male@xxxxxx
> Power Management Products NH Phone: 603.429.8705
> Texas Instruments CT Phone: 860.844.8183
> 7 Continental Blvd. NH FAX : 603.424.3460
> Merrimack, NH 03054-0399 USA CT FAX : 860.844.8806
>
> On Fri, 27 Apr 2001, Rick Brooks wrote:
>
> > Just to start up another discussion, I wanted to find out how many
> people
> > would support
> > the following concept for detecting when a PD receiving power becomes
> > disconnected.
> >
> > the concept:
> > $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
> >
> > 1) The PSE is responsible for detecting when a PD receiving DTE power
> > becomes disconnected.
> > If that event occurs, the PSE must turn off the power within some time
> frame
> > (100ms to 500ms ballpark?)
> >
> > 2) The PSE may use any of the following methods to detect this PD
> disconnect
> > event.
> >
> > a) the DC load current drop below "X" ma (10ma?)
> >
> > b) the ethernet link has dropped out
> >
> > c) another proven method (pending discussion and feasibility
> proof)
> > some suggestions:
> > 1) the AC probing circuit detects when the AC load changes
>
> > (opens)
> > 2) the PD modulation heartbeat current ceases
> > 3) the PD response to a given PSE code is wrong or absent
> > 4) other ideas
> >
> > $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
> >
> >
> > Please voice your opinions on this concept.
> > The motivation here is to lower the cost of delivering DTE power.
> >
> > thanks,
> > - Rick
> >
> >
>