Emerson 1420 Technical Note

2
Technical Note
00840-1600-4420, Rev AA
Smart Wireless Gateway 1420 with Power over Ethernet (PoE)
May 2015
Smart Wireless Gateway 1420 with Power over Ethernet (PoE)
3 PoE advantages
To save costs on planning, wiring and installation of networks, devices are supplied with power
directly via the ethernet cable (e.g. via a Cat 5/5e cable up to 100m). PoE makes the network
planning flexible, independent of power supply cabinets, and junction boxes. There are no extra
costs for the electrical wiring. An advantage of PoE is that you can install devices with an
ethernet interface in places of difficult access or in areas in which running cable would be
inconvenient. This in turn saves installation time and costs. This technology is in use today
typically in IP telephones, cameras, or wireless transmission devices such as WLAN Access
Points.
An excellent application is a Gateway connected to a Wi-Fi back haul unit; such as a Cisco
®
or
ProSoft
®
unit. For example a Cisco unit could power the Gateway or in another case the Gateway
could power the ProSoft unit as in a PFN with the addition of an external power supply.
4 Selecting devices to work with a PoE Gateway
The connecting device to the Gateway whether it is a PSE or a PD must be labeled as compliant
with IEEE 802.3af or IEEE 802.3at. Many companies use labels on their packaging such as PoE for
IEEE 802.3af or PoE+ for IEEE 802.3at. Check the specific manufacturer's specifications of any
device to make sure somewhere it references IEEE 802.3; otherwise it may not work.
The Gateway works as either a PoE PSE for IEEE 802.3af (sourcing 15 Watts) or PoE+ PSE for IEEE
802.3at (sourcing 25 Watts) depending on the input voltage to the Gateway from the power
supply. For 12 VDC nominal input, the Gateway can source 15 Watts. For 24 VDC nominal input,
the Gateway can source up to 25 Watts. No additional adjustment is necessary.
In the PoE PD mode, the Gateway draws its power over the selected ethernet cable from another
PoE IEEE 802.3 device either 802.3af or 802.3at.
Caution is needed in selecting a companion device to the Gateway for PoE. Not all devices
labeled PoE will function. Before 2003, there was no standard and companies developed their
own techniques for powering over an ethernet cable. These techniques are not always
interoperable. Before the standard, they used the term PoE on many of their products. Most new
products labeled PoE are IEEE compatible. Cisco products can be ordered with their old standard
(Online Power as it is sometimes referred to) or with the IEEE 802.3 PoE standard. Check with
the appropriate manufacturer if in doubt before purchasing/installing the connecting
equipment.
For reference, Cisco offers the following four versions:
1. Prestandard PoE (Online Power)
2. 802.3af-compliant PoE (15W)
3. 802.3at-compliant PoE Plus (PoE+) (25W)
4. Universal PoE (UPoE) (60W). (New Cisco standard, which Cisco claims is compatible
with IEEE 802.3af PoE and IEEE 802.3at PoE +)

Emerson 1420 Specifications

General

Brand	Emerson
Model	1420
Category	Gateway
Language	English