Lenze DDS v2.0 - Manual (Page 10)

Introduction to IEC 61131-3 programming
The communication model
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DDS-IEC61131 EN 2.0
3 The communication model
The communication model of IEC 61131-3 describes the data exchange of configuration elements
by means of
•
access paths
•
global variables
•
call parameters
•
communication organization units (IEC 61131-5)
These unambiguously defined interfaces support the modularization and thus the reuseability of
program parts.
3.1 Access paths
Defined access paths enable the configuration elements to communicate with each other and PLC
systems.
3.2 Global variables
Global variables enable easy communication between programs. They can be declared and used
in a configuration, resource and program.
3.3 Call parameters
Within a program, data is exchanged by means of call parameters, i.e. input and output variables.
Call parameters define interfaces for value transfers.
3.4 Communication organization units
Communication organization units provide communication services which are defined in part 5 of
IEC 61131 (in preparation).
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