Siemens S5-135U/155U - Manual (Page 164)

5-24
System Manual
C79000-G8576-C199-06
LEDs SI1 and SI2 indicate faults in communication via interfaces SI1
and SI2:
LED SI1 LED SI2 Cause
on on Communication is not possible at both interfaces.
Internal fault.
on off SI1:
No communication possible.
Internal fault.
SI2:
Interface is initialized and ready.
LED SI2 is always off if no interface module is
inserted.
off on SI1:
Interface is initialized and ready.
SI2:
No communication possible. Wrong module
inserted or internal fault.
off off Both interfaces are initialized and ready. LED SI2
is always off if no interface module is inserted.
Fault LEDs SI1
and SI2
CPUs, Memory Cards, Memory Submodules, Interface Submodules