Technical data

5.6 Errors in RUN and in RESTART
In the RUN mode, cyclic, time-driven or interrupt-driven program
execution or controller processing can be interrupted at operation
boundaries by the occurrence of certain errors or faults, e.g. power
failure in the central controller or block stack overflow.
Interruptions during initialization and in the RESTART mode cause
the restart program to be aborted and the CPU goes into the STOP
mode or calls the organization block intended for this error.
Interruptions occurring during the start-up program are handled in the
same way as in the CYCLE.
A distinction is made between problems that cause the CPU to go
directly to the STOP mode (e.g. STUEU) and problems that cause the
system program to call certain organization blocks that you can
program instead of the CPU going directly to the STOP mode (e.g.
ADF).
There is no way of responding via a user interface (error OB) to the
causes of interrupt and causes of error listed in the table below.
Errors which lead direct to
STOP
If these errors occur, an ISTACK is created in which the interrupt is
displayed.
Control bit or
ID in ISTACK
Explanation
STP STOP caused by the system program
(machine error), when an error OB is not
loaded, or there is a stop operation in the user
program
BAU Failure of the back-up battery in the central
controller
NAU Failure of the power supply to the central
controller
PEU Failure of the power supply to one or more
expansion units
STUEU Stack overflow in the interrupt stack
(ISTACK), nesting depth too great
STUEB Stack overflow in the block stack (BSTACK),
nesting depth too great
DOPP-FE Double call of an error program processing
level
Table 5-15
Causes of error and causes of interrupt in RESTART and RUN,
which lead direct to STOP
Errors in RUN and in RESTART
CPU 928B Programming Guide
5 - 38 C79000-B8576-C898-01