During normal operation, the LCD operates in idle mode and reports current status information, as shown in Figure 12.
Figure 12: LCD in Idle Mode

The lines in the display report the following information:
To add a message that alternates every 2 seconds with the default status messages, use the set chassis display message command. For more information, see the JUNOS Internet Software Operational Mode Command Reference: Protocols, Class of Service, Chassis, and Management.