Operating Modes Of A Cpu - Adam 821x Manual

CPU ADAM 821x

Operating modes of a CPU

General
Cyclic processing
Timer processing
Alarm controlled
operation
Priority based
processing
ADAM 8000 Manual CPU 821x – Rev 1.1
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 82xx peripherals the unit provides a powerful solution for process
automation applications within the System 82xx 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.
Chapter 1 Principles
1-13