Allied Telesis AT-8350GB Installation Manual page 86

Troubleshooting
86
If you are unable to establish a local management session with the
switch through the RS-232 Terminal Port on the back panel, do the
following:
Check to be sure that the null modem management cable is
securely connected to the RS-232 Terminal Port on the switch and
to the RS-232 port on the terminal or personal computer.
Check to be sure that you are using the null modem management
cable included with the switch.
Check to be sure that the operating parameters on the terminal or
the terminal emulation program, if you are using a personal
computer, have been set correctly. The default settings for the
RS232 Terminal Port can be found in Starting a Local
Management Session on page 78.
If you are managing a switch stack, check to be sure that the null
modem management cable is connected to the master switch,
not a slave switch.
If you have installed an optional redundant power supply, verify that the
RPS LED on the front of the power supply unit is ON. If the LED is OFF,
indicating that the unit is not receiving power, do the following:
Make sure that the power supply unit is securely connected to the
switch.
Make sure that the power cord of the power supply is securely
connected to the power source and to the AC connector on the
back panel of the power supply.
Verify that the power outlet has power by connecting another
device to it.
Try connecting the unit to another power source.
Try using a different power cord.
Check that the voltage from the power source is within the
required levels for your region.
If you have installed an expansion module, verify that the LED for the
port is ON. If the LED is OFF, do the following:
Check to make sure that the module is completely seated in the
expansion slot.