iPB4 Biometric Device Range
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Installation & User Guide
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Rev 07 ©2017-2018 iPulse Systems
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APPENDIX G
POE & ACCESS CONTROL
POWER OVER ETHERN ET: A BRIEF OVERVIEW
Power over Ethernet (PoE) is a technology for wired Ethernet LANs (local area networks) that allows the
electrical current necessary for the operation of specific devices to be carried over the data cables, thus
negating the need to have power at the end point of installation.
The concept behind this is to minimise the number of wires required for an installation. From a cabling
perspective at least, the end result is lower cost, easier maintenance, and greater installation flexibility
than with traditional wiring methods.
For PoE to work, the electrical current must go into the data cable at the power-supply end, and come out
at the device end, in such a way that the current is kept separate from the data signal so that neither
interferes with the other.
The current enters the cable by means of a component called an injector. If the device at the other end of
the cable is PoE compatible, then that device will function properly without modification. If the device is
not PoE compatible, then a component called a picker or tap must be installed to remove the current from
the cable before being connected to the device. This "picked-off" current can then be routed to the power
jack.
POE STANDARDS
The IEEE standard for PoE requires category 5 cable or higher for high power levels. Power is supplied in
common mode over two or more of the differential pairs of wires found in the Ethernet cables and comes
from a power supply within a PoE-enabled networking device such as an Ethernet switch or can be injected
into a cable run with a mid-span power supply.
The original IEEE 802.3af-2003 PoE standard provides up to 15.4 W of DC power (minimum 44 V DC and
350 mA to each device.
The updated IEEE 802.3at-2009 PoE standard also known as PoE+ or PoE plus, provides up to 25.5 W of
power (minimum 44 V DC and 575 mA. The 2009 standard prohibits a powered device from using all four
pairs for power.
DEVICES TYPICALLY US ED WITH POE
PoE provides both data and power connections in one cable, so equipment doesn't require a separate cable
for each need. For equipment that does not already have a power or data connection, PoE can be attractive
when the power demand is modest. For example, PoE is useful for IP telephones, wireless access points,
cameras with pan tilt and zoom (PTZ), and remote Ethernet switches.
DOWNSIDE OF POE WI TH BIOMETRICS
However, it is important to note that there are some significant potential downsides to PoE installations,
most specifically related to biometric installations.
Summary of Contents for iPB4
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