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Parallel Operation of Two Serial PG Interfaces
Parallel operation with
long-running functions
Parallel operation with
cyclic functions
User on PG 1
PG 1
informs the CPU
of the variables
to be output.
PG 1 requests the
current data
PG 1 requests the
current data
PG 1 requests the
current data.
PG 1 must wait until
the CPU is free.
PG 1 requests the
current data.
Fig. 11-7
Typical sequence of a cyclic function and parallel short-running function
11 - 22
The long-running functions "force" and ""program test" cannot
interrupt other functions and cannot be interrupted by other functions.
They can therefore not be executed parallel to other functions,
i.e. they are treated as a standard job "en bloc".
Cyclic functions can be executed both parallel to other cyclic and to
short-running functions. The following example shows the standard
sequence of the "status variables" function.
CPU 948
User on PG 2
PG 2 sends a job
PG 2 must wait until
the CPU is free.
Job sent by PG 2 is processed
PG 2 job complete
CPU 948 Programming Guide
C79000-G8576-C848-04
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