BECKHOFF CX50x0 - Manual (Page 68)

Notes on the documentation
66 CX50x0 - Hardware Documentation
6. Error handling and diagnostics
CPU basic moule
LEDs on the basic CPU module
Display LED Meaning
PWR Power supply
The Power LED comes on when the device is connected to a live power supply unit
(green).
TC TwinCAT status LED
TwinCAT is in Run mode (green)
TwinCAT is in Stop mode (red)
TwinCAT is in Config mode (blue)
HDD Read/Write Compact Flash (red)
Indicates access to the CF card.
FB1 Status LED1 for fieldbus
(function is written at the fieldbus interface)
FB2 Status LED2 for fieldbus
(function is written at the fieldbus interface)