Groups > sci.electronics.design > #459274

Re: Patch-panel fabrication (POE)

From	Don Y <blockedofcourse@foo.invalid>
Newsgroups	sci.electronics.design
Subject	Re: Patch-panel fabrication (POE)
Date	2017-05-07 12:24 -0700
Organization	A noiseless patient Spider
Message-ID	<oens2e$reg$1@dont-email.me> (permalink)
References	(3 earlier) <201700505d@crcomp.net> <oelj65$l44$1@dont-email.me> <oenljd$d9k$1@news.datemas.de> <oenq1n$kb3$1@dont-email.me> <oenqol$m37$1@news.datemas.de>

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On 5/7/2017 11:58 AM, Jan Panteltje wrote:
> On a sunny day (Sun, 7 May 2017 11:49:53 -0700) it happened Don Y
> <blockedofcourse@foo.invalid> wrote in <oenq1n$kb3$1@dont-email.me>:
>
>>> So it could cause damage to somebodies stuff if they plug it in and has that connector or a similar one.
>>> I am replacing all those connectors by HLJ6115ANL, also because it has 7,8 and 4,5 accessible and I need that to get the POE.
>>>  http://www.ebay.com/itm/271891560407
>>> But that is not something you can do with just any laptop... you plug in.
>>
>> Hmmm... are you suggesting the problem is OTHER devices that might get plugged
>> into my network?
>
> Exactly.

There's a hardware handshake that transpires between the PSE and a
potential PD.  The PSE looks for characteristic resistances on the signal
leads and, based on what it senses, determines what class of PD device
is being plugged.  If it senses a noncompliant device, it doesn't
apply power to the conductors.

This is how you prevent things like (analog!) telephones misplugged into PoE
jacks from wreaking havoc.

The trickier aspect is handling the case where the device remains
physically connected but you've elected to power the port down... then
up again.

>>> Also there seem to be more than a few POE standards:
>>>  http://pinoutguide.com/Net/poe_pinout.shtml
>>
>> Yes, I support both type a and type b power configurations -- because I can't
>> know, for sure, what other PSE/PD kit I may encounter in the future.  And,
>> there have been several "bastardizations" along the way (I have some Cisco
>> AP's that aren't compliant)
>>
>> I opted *not* to support PoE+ just because you have to draw the line
>> *somewhere* when it comes to centrally distributed power.  E.g., I suspect
>> when I design my "media (video) displays" -- in lieu of TV's -- I may find
>> the PoE supply inadequate.  But, I can tolerate a wall wart at that site as
>> there will obviously need to be AC mains available for the display *panel*.
>>
>> <shrug>
>>
>> My goal isn't perfection but, rather, a BIG step away from the more
>> traditional/naive way of powering distributed kit.  I suspect time
>> is on my side in that kit is always getting more capable and at lower
>> power levels.
>
> Yes, OK, I use these selectively to places where I am sure there is only my own equipment connected:
>  http://www.ebay.com/itm/151643358383
> with my own power supply of course.

Yes, Cisco has a little device that impresses 48V on the unused pairs
for their (older) AP's.  But, it's literally just an adapter from
48VDC wall wart "barrel connector" to midspan injector.  Plug one
of the devices you're worrying about, above, into it and it
will gladly deliver 48V @ 380mA to the "load".

Thread

Patch-panel fabrication Don Y <blockedofcourse@foo.invalid> - 2017-05-03 12:54 -0700
  Re: Patch-panel fabrication Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-05-03 13:23 -0700
    Re: Patch-panel fabrication Don Y <blockedofcourse@foo.invalid> - 2017-05-04 00:10 -0700
      Re: Patch-panel fabrication Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-05-04 11:27 -0700
        Re: Patch-panel fabrication Don Y <blockedofcourse@foo.invalid> - 2017-05-04 11:43 -0700
        Re: Patch-panel fabrication Clifford Heath <no.spam@please.net> - 2017-05-05 08:57 +1000
          Re: Patch-panel fabrication Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-05-06 05:47 -0700
        Re: Patch-panel fabrication krw@notreal.com - 2017-05-04 19:37 -0400
      Re: Patch-panel fabrication Neon John <no@never.com> - 2017-05-04 17:56 -0400
        Re: Patch-panel fabrication Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-05-06 05:46 -0700
      Re: Patch-panel fabrication Jasen Betts <jasen@xnet.co.nz> - 2017-05-11 05:57 +0000
        Re: Patch-panel fabrication Don Y <blockedofcourse@foo.invalid> - 2017-05-11 10:37 -0700
  Re: Patch-panel fabrication Martin Riddle <martin_ridd@verizon.net> - 2017-05-03 20:32 -0400
    Re: Patch-panel fabrication Don Y <blockedofcourse@foo.invalid> - 2017-05-03 23:59 -0700
  Re: Patch-panel fabrication Jasen Betts <jasen@xnet.co.nz> - 2017-05-04 06:34 +0000
    Re: Patch-panel fabrication Don Y <blockedofcourse@foo.invalid> - 2017-05-04 01:45 -0700
  Re: Patch-panel fabrication whit3rd <whit3rd@gmail.com> - 2017-05-04 01:52 -0700
    Re: Patch-panel fabrication Don Y <blockedofcourse@foo.invalid> - 2017-05-04 11:42 -0700
      Re: Patch-panel fabrication whit3rd <whit3rd@gmail.com> - 2017-05-04 21:22 -0700
        Re: Patch-panel fabrication Don Y <blockedofcourse@foo.invalid> - 2017-05-04 23:04 -0700
          Re: Patch-panel fabrication whit3rd <whit3rd@gmail.com> - 2017-05-04 23:24 -0700
            Re: Patch-panel fabrication Don Y <blockedofcourse@foo.invalid> - 2017-05-05 00:19 -0700
              Re: Patch-panel fabrication whit3rd <whit3rd@gmail.com> - 2017-05-05 00:45 -0700
                Re: Patch-panel fabrication Don Y <blockedofcourse@foo.invalid> - 2017-05-05 02:17 -0700
  Re: Patch-panel fabrication jrwalliker@gmail.com - 2017-05-04 08:40 -0700
    Re: Patch-panel fabrication Don Y <blockedofcourse@foo.invalid> - 2017-05-04 10:12 -0700
      Re: Patch-panel fabrication jrwalliker@gmail.com - 2017-05-04 10:27 -0700
        Re: Patch-panel fabrication Don Y <blockedofcourse@foo.invalid> - 2017-05-04 11:01 -0700
          Re: Patch-panel fabrication makolber@yahoo.com - 2017-05-04 11:18 -0700
            Re: Patch-panel fabrication Don Y <blockedofcourse@foo.invalid> - 2017-05-04 11:27 -0700
      Re: Patch-panel fabrication Don Kuenz <g@crcomp.net> - 2017-05-06 05:33 +0000
        Re: Patch-panel fabrication Don Y <blockedofcourse@foo.invalid> - 2017-05-06 15:40 -0700
          Re: Patch-panel fabrication whit3rd <whit3rd@gmail.com> - 2017-05-06 20:15 -0700
            Re: Patch-panel fabrication Don Y <blockedofcourse@foo.invalid> - 2017-05-06 23:47 -0700
              Re: Patch-panel fabrication whit3rd <whit3rd@gmail.com> - 2017-05-07 03:51 -0700
                Re: Patch-panel fabrication Don Y <blockedofcourse@foo.invalid> - 2017-05-07 05:20 -0700
          Re: Patch-panel fabrication (POE) Jan Panteltje <pNaOnStPeAlMtje@yahoo.com> - 2017-05-07 17:30 +0000
            Re: Patch-panel fabrication (POE) Don Y <blockedofcourse@foo.invalid> - 2017-05-07 11:49 -0700
              Re: Patch-panel fabrication (POE) Jan Panteltje <pNaOnStPeAlMtje@yahoo.com> - 2017-05-07 18:58 +0000
                Re: Patch-panel fabrication (POE) Don Y <blockedofcourse@foo.invalid> - 2017-05-07 12:24 -0700
                Re: Patch-panel fabrication (POE) Jan Panteltje <pNaOnStPeAlMtje@yahoo.com> - 2017-05-07 19:48 +0000
                Re: Patch-panel fabrication (POE) Don Y <blockedofcourse@foo.invalid> - 2017-05-07 13:29 -0700
                Re: Patch-panel fabrication (POE) Jan Panteltje <pNaOnStPeAlMtje@yahoo.com> - 2017-05-07 20:54 +0000
  Re: Patch-panel fabrication Allan Herriman <allanherriman@hotmail.com> - 2017-05-07 10:35 +0000
    Re: Patch-panel fabrication Don Y <blockedofcourse@foo.invalid> - 2017-05-07 05:26 -0700

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