Siemens CPU 948 User Manual

Parallel operation with
long-running functions
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".
Parallel operation with
cyclic functions
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.
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 requests the
current data.
PG 1 must wait until
the CPU is free.
Job sent by PG 2 is processed
PG 2 must wait until
the CPU is free.
PG 2 sends a job
PG 2 job complete
CPU 948
User on PG 1
User on PG 2
Fig. 11-7 Typical sequence of a cyclic function and parallel short-running function
Parallel Operation of Two Serial PG Interfaces
CPU 948 Programming Guide
11 - 22 C79000-G8576-C848-04

Siemens CPU 948 Specifications

General

Brand	Siemens
Model	CPU 948
Category	Controller
Language	English