Re: [8023-POEP] Fw: Rejected posting to STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
Hi Bob,
It sounds like you have additional information about the
incident not included in the liason letter.
What can you tell us about the electrical environment of
the PSE, channel, and (non-PD) end-point device discussed in the liason?
What can you tell us about the physical channel
implementation?
Can you provide the specific requirements that you allude
to in your posting?
Thanks and Regards,
Martin
Martin
Patoka
Systems Engineering Manager
Texas Instruments
O:
214-567-5487
mpatoka@xxxxxx
-----
Message from Robert E Lounsbury <relounsbury@xxxxxxxxxxxxxxx> on Wed, 8
Jul 2009 06:38:06 -0400 -----
|
To:
| Hugh Barrass
<hbarrass@xxxxxxxxx>
|
|
cc:
| owner-stds-802-3-poep@xxxxxxxx,
STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
|
|
Subject:
| Re: [8023-POEP] Liaison letter from IEC TC65/SC65C/JWG10
- Power over Ethernet performance in industrial
environments |
Hello Hugh,
Dave,
Please read the liaison letter. Please disregard the damaged
device. The damaged device only served to start the discussion in IEC.
The letter is asking two very basic questions that might precipitate some
considerations in the specification. First Dave mentions noise coming from
the device loads back onto the channel. This was one of the questions in the
letter. Dave alludes to violating the specification. Please point to
where in the specification where noise produced and coupled back to the PoE
channel is defined, limited or otherwise discussed. Second the letter asks
if the PoE TG has considered analyzed what might happen if there is Radiated,
conducted or other environmental noise in the area where the PoE system is
installed might cause problems during the probing process. This has nothing to
do with any design flaws of a product but merely the environment. If you
consider Industrial noise levels as defined by IEC out of the scope for 802.3at,
then please respond indicating so. Then we might be in a position to disallow
PoE in industrial. Thanks for your time
Regards
Rockwell Automation
Bob Lounsbury – Principal
Engineer
Control
and Visualization Business
1 Allen-Bradley Drive, Mayfield Heights,
OH. 44124
Tel:
+1.440.646.4297
Fax: +1.440.646.3076
Cell: +1.440.610.4485
email: relounsbury@xxxxxxxxxxxxxxx
Hugh Barrass
<hbarrass@xxxxxxxxx>
Sent by:
owner-stds-802-3-poep@xxxxxxxx
07/07/2009 01:51 PM
|
Please respond
to
Hugh Barrass
<hbarrass@xxxxxxxxx> |
|
|
To
| STDS-802-3-POEP@xxxxxxxxxxxxxxxxx
|
|
cc
|
|
|
Subject
| Re: [8023-POEP] Liaison letter from
IEC TC65/SC65C/JWG10 - Power over Ethernet performance in industrial
environments |
|
David,
I can see that the
liaison from IEC has caused some interesting
discussion amongst PoE experts
(and myself), however I think that we are
being asked to comment on what may
well be design flaws in specific
products and I do not think that is a
healthy discussion within 802.3.
I suggest that we should send a reply
along the following
lines:
==========================================
The problems
described in your liaison spurred some vigorous discussion
amongst our task
force members regarding possible causes for the damage
that you describe.
However the members are not aware of any similar
reports that might indicate
a systemic problem with 802.3 compliant
equipment. It is the opinion of the
members of IEEE P802.3at Task Force
that the standard allows product
manufacturers to build reliable and
interoperable equipment that will meet
the requirements for supplying
power over Ethernet in many environments.
However, the standard does not
define how a manufacturer must build the
product to ensure reliability
or how an installer should ensure that the
media is suitable for correct
operation within the standard. We suggest that
you should work with the
equipment manufacturers involved to determine
whether the failure is the
result of a systemic problem with the standard
and whether a specific
amendment may be required.
With respect to the
bit error rate performance of 802.3 links when power
is being supplied over
the same link, the members of IEEE P802.3at Task
Force believe that a
compliant system supplying power over an 802.3 link
will not perturb the
channel sufficiently to degrade the performance of
the underlying link.
However, it is the responsibility of the product
manufacturer to ensure that
noise introduced by the load does not couple
to the link and violate the
power over Ethernet specifications or the
channel specifications required
for the link. Similarly it is the
responsibility of the system installer
that the channel characteristics
are met in the presence of environmental
noise.
===========================================
Hugh.
David
Law wrote:
>All,
>
>The IEEE 802.3 Working Group has
received a liaison letter from IEC
>TC65/SC65C/JWG10, Industrial process
measurement, control and
>automation/Industrial networks with respect to
Power over Ethernet
>performance in industrial environments.
>
>I just wanted to inform you that I intend to delegate the
generation of a
>draft response to the IEEE P802.3at DTE Power
Enhancements Task Force
>during the plenary week in July. The draft
response will be consider and
>then voted upon at the closing IEEE 802.3
Working Group plenary as part of
>the IEEE P802.3at closing report. You
therefore may wish to review the
>letter prior to the meeting, the letter
can be accessed at the URL [
>http://www.ieee802.org/3/minutes/jul09/0709_IEC_SC65C_JWG10_to_802_3.pdf
>].
>
>Best regards,
> David Law
>
IEEE 802.3 Working Group Chair
>
>
>