Siemens S5-155U System Manual page 188

LEDs for fault indication and
signalling
System Manual
C79000-B8576-C199-03
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 928 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 928),
• •
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.
ADF LED
on The user program has referenced an I/O address under
which no module is inserted.
ZYK LED
on The maximum cycle time has been exceeded.
BASP LED
on Command output is inhibited and the digital outputs
will be directly switched to the safe state.
A detailed description of interrupt and error handling can be found in
the CPU 928 Programming Guide.
CPU 928
5
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