Panasonic KX-TD500 System Reference Manual page 1521

F. Monitor
1.00 SYM command (System
Maintenance Monitor)
Current operating status of the following items
can be displayed on the screen by entering SYM
command.
Command Format
OPE>SYM + Index
(Index)
1 : System Status
2 : Card Status
3 : Port Status (Basic Shelf)
4 : Port Status (Expansion Shelf 1)
5 : Port Status (Expansion Shelf 2)
6 : Conference Trunk Status
16-F-1