Lantronix
SESPM1040-541-LT-xx Install Guide
33772 Rev. F
Page
48
of
64
PoE
Troubleshooting
1.
Get as much detail as possible regarding the symptom, including any system messages from the PoE switch.
For example, does a PD not power up at all, or does it power up briefly and then power down?
2.
Determine if the trouble occurred on initial installation or after the PD had been working normally?
3.
If the trouble started after the PD was working, what changed? Were there any hardware or software
changes?
4.
Verify that the port is not shut down, disabled, or errored.
5.
Verify that the Ethernet cable from the PD to the switch port is good.
6.
Verify that the total cable length from the switch front panel to the connected PD is not more than 100
meters. Some of the power from the switch port is dissipated in the cable due to wire resistance, especially
on cables as long as 100 meters. Only the remaining power is available to the PD.
7.
Verify that the PSE switch power budget can power the PD. If the switch power budget is depleted,
additional PDs will not power-on when connected to a PoE port. Verify that the switch power budget
(available PoE) is not depleted before or after the PD is connected. Verify that sufficient power is available
for the PD type.
8.
Verify if non-powered Ethernet devices can establish an Ethernet link on any port and that PoE devices do
not power up on the same port.
9.
Review alarms reported previously by system messages.
10.
If a working IP camera or WAP intermittently reloads or disconnects from inline power, verify all electrical
connections from the switch to the PD. An unreliable connection results in power interruptions and
intermittent PD operation, such as PD disconnects and reloads.
11.
Check for changes in the electrical environment at the switch site. What is happening at the PD when the
disconnect occurs? Check for error messages reported by the switch at the same time of the disconnect.
12.
Verify that an IP camera is not losing access just before a reload occurs (a network problem, not a PoE
problem).
13.
Pre-standard and post-standard IP camera may use different detection and connect / disconnect methods.
Note that PD detection occurs when an Ethernet device is first connected to a PoE port. If a non-PoE device
is connected to a PoE port, detection is deactivated. If the non-PoE device is later disconnected and replaced
by a PD, the switch may not detect it immediately.
14.
Verify that the PD is not causing an overcurrent condition on the port. Specifically: does the IP camera WAP,
or lighting initially power on and then disconnect? If so, the problem may be an initial current surge that
exceeds a current-limit threshold for the switch port. Some PDs may have excessive “surge in” current when
first connected to a PoE port. The switch initially provides power to the port, and then quickly removes
power due to a momentary overcurrent condition. The PD starts to power up, but then quickly powers
down.
15.
The SESPM1040-541LT-xx has voltage and current regulators that detect an overcurrent threshold and
disconnect power from the line. This prevents excessive current from being delivered by the PoE port, which
could possibly result in damage to port-level components.