Nesting with "interruptability
at operation boundaries"
While the "program test" function is running, the other program
execution levels can be activated, if the mode "interruptability at
operation boundaries" is set.
When an operation has been processed at a breakpoint and a different
program execution level is called at this point (e.g. an error OB or an
interrupt OB) this is first processed completely before the program is
continued at the next breakpoint.
Note
The system program reads data and outputs it at an operation
boundary. At this point, all related program execution levels have
not yet been processed.
The sequence of the "program test" function is illustrated in Fig. 11-2.
Note
If an operation has been processed at a breakpoint and activation
of a different program execution level is requested, you can set a
breakpoint at an operation in the different program execution
level (e.g., you can look at a QVZ error OB directly after an
operation that triggers a QVZ error).
Execute operation
and
read data
Execute operation
and
read data
< <<<<<
< <<<<<
1st breakpoint
WAIT STATE (output data)
WAIT STATE (output data)
Process interrupt, timed
interrrupt, error OB
Process interrupt, timed
interrupt, error OB
Next
breakpoint
Fig. 11-2 Sequence of "program test"
PG Functions
CPU 948 Programming Guide
11 - 12 C79000-G8576-C848-04
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