Siemens S5-155U System Manual page 163

LEDs for fault indication and
signalling
System Manual
C79000-B8576-C199-03
Given in the following overview are the causes for LEDs lighting up:
QVZ LED
on A module addressed by the program no longer
acknowledges although/because
• • it either acknowledged in single-processor operation
upon restart of the CPU 948 in the area of the
process image (IB0 to 127, QB0 to 127) and has
been entered as present in the so-called 9th track;
• • or it has been entered in multi or single-processor
operation in DB 1 (address list) and has been
recognized as present during the restart;
• • or it was addressed in direct access by operations
LPY, LPW, TPY, TPW, LOY, LOW, TOY, TOW;
• • or the data handling blocks cannot access the
module.
Possible causes:
• • Module failure
• • Module removed during operation, in the STOP state
or in the Off state without subsequent restart.
A timeout occurred during access to the user memory.
ADF LED
on The user program has referred to an address in the
process image under which no module was inserted in
the I/Os or was not entered in DB 1 during the last
restart.
ZYK LED
on The preset cycle time monitor has responded and
cyclic program processing is interrupted.
BASP LED
on Command output is inhibited and the digital outputs
will be directly switched to the safe state (0).
INIT LED
on This LED is continuously lit for a short time during
initialization after power ON and during operation in
the event of system faults.
A detailed description of interrupt and error handling can be found in
the CPU 948 Programming Guide.
CPU 948
5
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