|Thread Links||Date Links|
|Thread Prev||Thread Next||Thread Index||Date Prev||Date Next||Date Index|
Regarding your specific questions:
1. Noise interference with PoE detection.
Unconstrained noise will, of course, interfere with the detection process and may even cause a false detection. However, PoE was design to work on channels that are suitable for Ethernet communication. If the installation is compliant with the appropriate channel criteria (whether CAT-3, CAT-5 etc.) for the type of Ethernet interface required then the PoE scheme is very robust. Note that a compliant installation is not simply any installation that uses CAT-5 labeled cable, please read the relevant cable installation documents for further information.
If you have issues with media performance in an industrial environment then you should talk to a media standards development organization.
2. Coupled noise from PoE interfering with communication.
802.3, clause 33.2.8 has specific requirements on the power source regarding load regulation and noise; clause 33.3.5 has specific restrictions on powered device inrush, ripple and noise. Clearly the noise within these limits will have some (albeit small) effect on the communication but the onus is on the equipment manufacturers of systems that support PoE to ensure that their interfaces tolerate the increased noise within the specifications of clause 33. It is also part of the design challenge to ensure that whatever noise is generated from switching power within a system is coupled onto the interface within the limits prescribed.
IEEE 802.3 is a standards development organization. It does not offer consultancy, nor does it assess compliance of any implementation or installation. If part of the standard appears to be ambiguous then you may enter an interpretation request; if there appears to be a deficiency then you may enter a maintenance request.
In the meantime, I stand by what I wrote as a response to the liaison request.
Robert E Lounsbury wrote: