Power-over-Ethernet is for more than IP phones, Wi-Fi access points and surveillance cameras. It can be used anywhere there’s a low-power device that would benefit from continuous power and the reliability of Ethernet connectivity. Assuming your network switch (or POE injector) is connected to a UPS, POE allows the attached devices to remain powered in the event of a power failure.
In my home and office, I use POE to connect and power a number of Raspberry Pi single-board computers configured as music players. The RPi3 B+ isn’t natively POE capable, so I use a POE splitter like the one pictured here.
iDevices are getting used in innumerable ways these days. Some years back you may recall my examination of the Mocet Communicator, an iPad accessory that turned it into an executive desk phone. Behringer’s X AIR XR18 is an audio mixer with iDevice remote control. The Cerevo LiveWedge is a video production switcher with an iPad-centric control scheme. These are just a few examples of iDevices assuming a key role in the control scheme of a more sophisticated device.
What the Mocet device highlighted is that dependence upon Wi-Fi is not always an optimal solution for connectivity. It provides Ethernet connectivity and could be powered using standard 802.11af power-over-Ethernet.
While supporting 10/100/1000 Mb Ethernet networks, the USB subsystem of the Lightning port delivers 225 Mbps. The interface is 802.11af compliant, capable of drawing up to 15.4 watts from the network line to keep the iDevice charged.
A single solution to providing reliable power and connectivity strikes me as massively appealing. I can see this as useful in any situation where an iDevice is in a dedicated application.
Over the years I’ve come to admire 802.3af standard power-over-Ethernet (aka P.O.E.), even for small- or home-office applications. What follows is an introduction to the topic, and some novel ideas about its use in possibly unexpected applications.
Some time ago I received a Raspberry Pi B+ as a gift. It had been on my amazon wish list, and for good reason. It looked like one practical approach to emulating the venerable Logitech Squeezebox, which to this day serves as the basis for music playback hereabouts.
Since we were not expanding our music playback scheme there was at first little motivation to got ahead with this effort. That is, until the analog outputs of our existing fleet of Squeezeboxes started to fail. Eventually the analog outputs become unusable, the result of failing electrolytic capacitors. Three of our five SB3s now suffer this malady.
The .e4 blog has a good new post on power-over-ethernet, which I see as an often overlooked area of SOHO VoIP. It goes into some detail P.O.E. network switches, power management and mid-span P.O.E injectors.
Just last week we suffered a power outage that took down my entire office for about two hours. That is, it took down everything that wasn’t on the UPS. At the time I was on a tech support call with a customer. Happily, my IP650 and all the core network components get UPS power, some via P.O.E.. The UPS power only lasted about 45 minutes, but that was enough to let me resolve my tech support situation.
While some of our larger offices have P.O.E. capable network switches I use a couple of simple single-port mid-span power injectors from Aastra. Why? They’re simply a better, and more cost effective solution for my small office. I only need to power a couple of devices over the ethernet, just my Polycom desk phones. However, I need gigabit ethernet bandwidth in a number of places. POE capable gigabit switches were on the expensive side when last I reworked the office network. In contrast, single port power injectors can be had for around $40 each.
It started out an uneventful day, the third day in an entire week that I expected to spend in my home office. That’s something of a rarity in recent times. I was enjoying it, catching up on matters around here, and addressing tech support calls as they arose. I was on just such a call when, to my considerable surprise, the power went out.
The sudden loss of power is not enough to disrupt my phone call beyond my own expression of surprise. As I’ve documented elsewhere, I’ve taken steps to ensure that critical infrastructure around here is on a UPS. To paraphrase Frank Herbert, “The electrons must flow.” In fact, it occurred to me that this afternoon was an opportune time to ascertain just how sound my planning had been.