Rockwell Automation 1783-BMxxx Stratix 5700 Ethernet Managed Switches User Manual - Manual (Page 87)

Rockwell Automation Publication 1783-UM004E-EN-P - June 2014 87
Switch Software Features Chapter 3
If the switch detects a fault caused by an undervoltage, overvoltage,
overtemperature, oscillator-fault, or short-circuit condition, it turns off power to
the port, generates a syslog message, and updates the power budget and status
indicators.
Power Management Modes
PoE ports support these modes:
• Auto (default)—The port automatically detects if the connected device
requires power. This is the default mode. If the port discovers a connected
powered device and the module has enough power, it grants power,
updates the power budget, turns on power to the port on a first-come,
first-served basis, and updates the status indicators.
If enough power is available for all powered devices connected to the
switch, power is turned on to all devices. If there is not enough available
power to accommodate all connected devices and if a device is
disconnected and reconnected while other devices are waiting for power, it
cannot be determined which devices are granted or are denied power.
If granting power exceeds the system power budget, the switch denies
power, verifies that power to the port is turned off, generates a syslog
message, and updates the status indicators. After power has been denied,
the switch periodically rechecks the power budget and continues to
attempt to grant the request for power.
If a device being powered by the switch is then connected to wall power,
the switch can continue to power the device. The switch can continue to
report that it is still powering the device whether the device is being
powered by the switch or receiving power from an AC power source.
If a powered device is removed, the switch automatically detects the
disconnect and removes power from the port. You can connect a
nonpowered device without damaging it.
You can specify the maximum wattage that is allowed on the port. If the
IEEE-class maximum wattage of the powered device is greater than the
configured maximum value, the switch does not provide power to the port.
If the switch powers a powered Cisco end device, but the powered device
later requests through CDP messages more than the configured maximum
value, the switch removes power to the port. The power that was allocated
to the powered device is reclaimed into the global power budget. If you do
not specify a wattage, the switch delivers the maximum value.