Check with the manufacturer for the specifications of the cable being used to determine
the power versus length requirements. Multiple powered Ethernet cables running in the
same location must be considered for total temperature rise. Most Ethernet cable
suppliers have charts for PoE usage on their websites.
Typically, Cat 5 should handle most installations with runs up to 100 meters
(approximately 300 feet). The use of Cat 3 is not recommended in any installation PoE or
non-PoE, Cat 3 may work for some lower power short run applications, but overall it has
poorer data handling and lower power capability. Cat 6 and Cat 7 are respectively better
than Cat 5.
PoE FAQs
Does the old 1420 Gateway hardware have PoE?
No, not IEEE PoE; in the current 1420 Gateway there is a third Ethernet port on the far left
of the connector board (closest to the hinge). This port has a cover on it; in the manual it is
labeled “Ethernet 2 with Power.” This connector is connected to Ethernet port 2 and the
spare Ethernet wires in this connector are bridged to the input power lines to the Gateway.
This was designed for special applications and is not recommended for normal use. This
connector can damage computer and other equipment connected to it if used improperly
and has been removed as it is not needed in the new PoE design.
What do I have to do to order IEEE PoE on a 1420 Gateway?
There is no specific option code for PoE. In time, all 1420 Gateways will have PoE. Initially
PoE will be offered by approvals codes as PoE is approved for that application. For
example, typically N5 or N6 approvals take the least time. These approvals codes when
approved for PoE would automatically ship with the new hardware. Approval codes like N3
or N4, which typically take a longer time, would ship with PoE at a later date. Contact your
Emerson Sales Representative to find out if a particular code has been approved for PoE.
It should be also noted that all PoE units shipped are configured as a PoE PD on port 1. By
using the jumpers included with the unit, the installer configures the unit during
installation as to mode and port of PoE operation if desired. See the #unique_48/
unique_48_Connect_42_Rae17094 for jumpering diagrams.
If I am not using PoE, how should I program the Gateway?
Program the 1420 Gateway as a PoE PD on either port; then connect up the local power
supply (24 or 12 VDC) to the power input terminals of the Gateway. There is no problem if
the Gateway is programed as a PD and has local power too. The Gateway working as a PD
when it sees local power switches to the local power instead of the Ethernet PoE. See
#unique_48/unique_48_Connect_42_Rae17094 for jumpering diagrams.
What type of power supply should I use with the PoE Gateway in the PSE mode?
A Class 1 power supply is strongly recommended for all Gateway applications for improved
safety. The power supply should be a 24 or 12 VDC unit. 24 VDC allows more power to be
sourced in the PSE mode. The power supply should be able to handle at least 30 Watts if
using PSE; for good operating margin it would be advisable to consider at least a 50 Watt
supply.
Installation
Reference Manual
September 2020 00809-0200-4420
30 Emerson.com/Rosemount
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