Siemens S5-155U System Manual page 177

CPU 928B
Status indicators
LEDs for fault indication and
signalling
5 - 28
RUN STOP Status
LED LED
on off The CPU is in the RUN state.
off on The CPU is in the STOP state. After a stop
request by switch or PG function, the STOP
LED is continuously lit because the transition
to the STOP state was requested by the user or,
in multiprocessor operation, by another CPU,
and was not caused by the CPU itself.
off off The CPU is in the INITIAL START or
program check state.
off slow The CPU is in the STOP state. The CPU has
flashing caused a transition to the STOP state (possibly
also for the other CPUs). If you set the mode
switch to STOP, the flashing LED becomes
continuously lit.
off rapid The CPU is in the STOP state. An overall reset
flashing has been requested. This request can be
initiated by the CPU itself or by operator
action.
QVZ LED
on During direct access or process image update, a module
addressed by the program no longer acknowledges
although
• •
either it has acknowledged in single-processor
operation upon reset of the CPU 928B in the area of
the process image (IB 0 to 127, QB 0 to 127) and
has been entered as present in the "9th track" (see
Programming Guide, CPU 928B),
• •
or it has been entered in DB 1 (address list) in
multiprocessor or single-processor operation and
has been recognized as present during the reset.
Possible causes
• •
Module failure.
• •
Module was pulled out during operation, in the
STOP state or in the Off state without a subsequent
reset.
System Manual
C79000-B8576-C199-03