Level Meaning Priority
Error levels
WEFES/WEFEH
ZYK
SUF
TRAF
ADF
QVZ
PARE
KB
KDB
FEDBX
Collision of timed interrupts
Cycle error
Substitution error
Transfer/load error
Addressing error
Timeout
Parity error
Called code block does not exist
Called data block does not exist
Error generating a data block, DB or DX
Each error handling
routine has the highest
priority. If an error
occurs, the
corresponding error
level is nested in
immediately.
Program execution levels in SOFT STOP
COMMUNICATION START-UP
COMMUNICATION
Preparation (start-up) for communication
Cyclic processing of communication
–
Program processing levels in START-UP
COLD RESTART
WARM RESTART
Defined start of the user program
Continuation of the user program at the
point of interruption
–
Program execution levels in RUN
TIMED INTERRUPTS
PROCESS INTERRUPTS
CYCLE
Time-controlled program execution
Interrupt-driven program execution
Cyclic program execution
Ascending
1)
priority
(default)
1)
The default can be changed by selecting parameters for DX 0 (refer to Chapter 7).
Processing via the system
program
A specific system program is responsible for each level.
Interrupt stack (ISTACK)
If an interrupt occurs, the system program sets up an information field
in the ISTACK for each level, to allow it to continue in the interrupted
level after servicing the interrupt.
Table 4-1 Program execution levels
Program Execution Levels
CPU 948 Programming Guide
C79000-G8576-C848-04
4 - 5
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