Siemens S5-135U/155U appendix RUN Stop LED

CPUs, Memory Cards, Memory Submodules, Interface Submodules

Status Indicators Given in the following overview are the functions of the RUN, STOP and SYS FAULT status LEDs.

The STOP LED indicates a soft stop; the SYS FAULT LED indicates a hard

STOP.

The CPU 948 can process a user program (OB 39) cyclically at the soft STOP, but the digital outputs remain inhibited. At the hard STOP, no program can run and the CPU has ªstopped.º This state can only be exited by switching the system voltage off and on again.

RUN	STOP
LED	LED
on	off
on	on
off	off
off	on
off	rapid
	flashing
off	slow
	flashing
off	off

SYS	Status
FAULT
LED
off	The CPU is in the RUN state (cyclic
	operation).
on	Appears briefly after power-up of the unit.
off	CPU is in the initial start or program check
	state.
off	CPU is in the soft STOP state.
off	CPU is in the soft STOP state.
	Overall reset has been requested by switch or
	from the operating system.
off	CPU is in the soft STOP state. An error has
	occurred; see the CPU 948 Programming
	Guide for possible causes.
on	CPU is in the hard STOP state. No program
	processing is taking place. You can only exit
	from this state by switching the system
	voltage off and on again.

5-22	System Manual
	C79000-G8576-C199-06