Siemens Simatic M7-400 Reference Manual page 435

Meaning of the Status and Fault LEDs
The status and fault LEDs are explained in Table 11-4 in the order in which they are
arranged on the CPU 486-3 and CPU 488-3 modules. The following status and
fault LEDs are available:
Table 11-4 Meaning of the Status and Fault LEDs on the CPU 486-3 and CPU 488-3
LED
INTF (red)
EXTF (red)
SD (green)
HD (green)
USR1
(yellow)
USR2
(yellow)
RUN
(green)
STOP
(yellow)
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
Meaning
Internal or external Lights up in the event of:
fault indicator •
Hardware faults
•
Firmware faults
•
Programming faults
•
Parameter assignment faults
•
Computational faults
•
Timer faults
•
Memory card faults
•
I/O faults
Use the programming device for precise fault-finding
(read out diagnostic buffer).
Access to memory Lights up if read or write access to the memory card is
card taking place.
Hard disk access Lights up if read or write access to the hard disk of the
mass storage module is taking place
Special LED for Can be assigned by the user (see Programming
Manual)
the user program
(User)
Special LED for
the user program
(User)
"RUN" state LED Lights up if the system software is loaded and user
programs are running
(I/O access enabled).
•
"STOP" state LED Lights up when the user program of the
programmable module is not controlling the
process (I/O access disabled)
•
Flashes when a memory reset is requested or is
being performed
CPUs for M7-400
Explanations
11-7