Siemens SINUMERIK 828D Manual page 79

LED displays on the front
The three LEDs located behind the protective flap on the front side of the PPU have the
following significance:
Name
RDY
NC
CF
NOTICE
If the LED is lit, the CompactFlash card must not be removed!
Non-compliance can result in damage to the CompactFlash card.
PPU
Manual, 03/2013, 6FC5397-2DP40-3BA1
Color Status
Green Is lit
Yellow Is lit
Flashing
Red Is lit
Yellow Cyclic flashing
Yellow Is lit
6.4 PLC I/O Interface based on PROFINET
Meaning
NC Ready and PLC in run mode.
PLC in stop mode
Power-up
NC in stop mode:
When booting, if NC Ready is not yet available

Critical fault (power off/on necessary)

NC operation
Accessing the CompactFlash card.
Interface description
79