Kuhnke Electronics Instruction Manual

4.3.1 Operating System
Function Libraries
The operating system defines all of the controller's
properties. It is part of the Ventura Remote PLC delivery
package and is stored in the internal flash EPROM.
The best part of the operating system is made up of its
real-time kernel, ARTOS.
ARTOS provides options for optimising the control
processes with regard to the installation of interrupt
routines or parallel programs, for example.
To be able to make best use of these options, you should
have some understanding of how the operating system
actually works.
ARTOS provides Ventura Remote PLC with pre-emptive
multitasking.
Pre-emptive multitasking means that several processes
(tasks) can be run and that the processor's computing
time is cut up into slices of a defined size.
A Scheduler (dispatcher) allocates time slices to the
processes during which program actions can be
performed.
When a process's time slice comes to an end the process
is interrupted and another process is allocated a time
slice.
A process could be anything like the CoDeSys runtime
system (see section 4.3.2) or PROFIBUS communication
routines. Running a function would set up another process
which is capable of interrupting the CoDeSys runtime
system.
Programs that the CoDeSys Task Configurator utility
assigned to specified events will not interrupt the
CoDeSys runtime system, though, because they are
processed only when they are "out of the way", e.g. when
the main program, PLC_PRG, has been completed.
(See pages 59 and 70)
4.3.2 The CoDeSys Runtime System
The CoDeSys runtime system is a process embedded in
the multitasking system of Ventura Remote PLC.
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