BECKHOFF CX9000 - Manual (Page 43)

Error handling and diagnostics
Embedded PC 41
5. Error handling and diagnostics
CPU basic module
LEDs Basic CPU-module (E-Bus)
Display LED Meaning
red TwinCAT is in STOP mode
green TwinCAT is in RUN mode
blue TwinCAT is in CONFIG mode
PWR
off System is offline
LAN 1 LAN Link , (green)
LINK/ACTIVITY for first switched LAN PORT (CX9000_N000)
LAN 2 LAN Link, (green)
LINK/ACTIVITY for second switched LAN PORT (CX9000_N000)
L / A (Link Activity) flashes in traffic on E-bus.
HDD Read/Write Compact Flash (red)
Indicates access to the CF card.