Can the L4490A/L4491A mainframe be password protected when using LAN?
From the L4490A/L4491A web interface, select "View & Modify Configuration" and select "Modify Configuration" to set and change the password. A LXI reset (pressing the recessed 'LAN Reset' button on the front or rear panel) will restore the password to the factory default of no password – see the manual for a complete list of the factory default LAN configuration settings.