Siemens CPU 948 User Manual

Time-controlled processing In addition to the cyclic processing, time-controlled processing is
also available for processes requiring control signals at constant
intervals, e.g. non-time critical monitoring functions performed every
second.
Interrupt-driven processing If the reaction to a particular process signal must be particularly fast, this
should be handled with interrupt-driven processing. With, for example,
a system interrupt, triggered via an interrupt generating module, you
can activate a special processing section within your program.
Processing according to
priority
The types of processing listed above are handled by the CPU
according to their priority.
Since a fast reaction is required to a time or interrupt event, the CPU
interrupts cyclic processing to handle a time or interrupt event. Cyclic
processing therefore has the lowest priority.
Whether or not the time-controlled processing is more important than
the interrupt controlled processing depends, among other things, on
the particular task. For this reason, the priority of time and
interrupt-driven processing on the CPU 948 can be selected.
Typical Mode of Operation of a CPU
CPU 948 Programming Guide
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Siemens CPU 948 Specifications

General

Brand	Siemens
Model	CPU 948
Category	Controller
Language	English