Manual VIPA CPU 21x
Chapter 1
Principles
HB103E - Rev. 05/45
1-15
Operating modes of a CPU
These CPUs are intended for small and medium sized applications and are
supplied with an integrated 24V power supply. The CPU contains a
standard processor with internal program memory. In combination with the
System 200V peripherals the unit provides a powerful solution for process
automation applications within the System 200V family.
A CPU supports the following modes of operation:
•
cyclic processing
•
timer processing
•
alarm controlled processing
•
priority based processing
Cyclic
processing represents the major portion of all the processes that
are executed in the CPU. Identical sequences of operations are repeated in
a never ending cycle.
Where a process requires control signals at constant intervals you can
initiate certain operations based upon a
timer
, e.g. not critical monitoring
functions at one-second intervals.
If a process signal requires a quick response you would allocate this signal
to an
alarm controlled
procedure. An alarm may activate a procedure in
your program.
The above processes are handled by the CPU in accordance with their
priority
. Since a timer or an alarm event requires a quick reaction the CPU
will interrupt the cyclic processing when these high-priority events occur to
react to the event. Cyclic processing will resume once the reaction has
been processed. This means that cyclic processing has the lowest priority.
General
Cyclic processing
Timer processing
Alarm controlled
operation
Priority based
processing
Summary of Contents for CPU 21 Series
Page 1: ...Manual VIPA CPU 21x Order No VIPA HB103E Rev 05 45 ...
Page 2: ...Lerrzeichen ...
Page 6: ...About this Manual Manual VIPA CPU 21x Subject to change to cater for technical progress ...
Page 10: ...Contents Manual VIPA CPU 21x iv HB103E Rev 05 45 ...
Page 30: ...Chapter 1 Principles Manual VIPA CPU 21x 1 18 HB103E Rev 05 45 ...
Page 58: ...Chapter 2 Hardware description Manual VIPA CPU 21x 2 28 HB103E Rev 05 45 ...
Page 80: ...Chapter 3 Deployment CPU 21x Manual VIPA CPU 21x 3 22 HB103E Rev 05 45 ...
Page 178: ...Chapter 5 Deployment CPU 21x 2BT02 with H1 TCP IP Manual VIPA CPU 21x 5 48 HB103E Rev 05 45 ...