Siemens Simatic S7-400 - Manual (Page 434)

CPUs for M7-400
11-6
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
11.3.1 Status and Fault LEDs
Status and Fault LEDs
The CPU 486-3 and CPU 488-3 have the following status and fault LEDs:
INTF
EXTF
SD
HD
USR1
USR2
RUN
STOP
Figure 11-2 Status and Fault LEDs on the CPU 486-3 and CPU 488-3