Fig. 142 Representation Of A Created Plc Array Variable („Aui_Samples") To Link With Oversampling Pdos Of El3773 - Beckhoff EL3783 Documentation

Commissioning
Step 2a: Creation of a PLC variable within a POU
Within the TwinCAT 3 development environment an input variable as an array with respective amount than is
given by the oversampling factor have to be defined at first how it's illustrated in an example for the POU
"MAIN" and an oversampling factor 10 with structured text (ST) as follows:
PROGRAM MAIN
VAR
aU1_Samples AT%I* : ARRAY[0..9] OF INT;
END_VAR
The identification "AT%I*" stands for swapping out this array variable to link it with the process data objects
(PDOs) of a terminal/box later. Notice that at least the number of elements has to be the same as the
oversampling factor so that the indices can be set from 0 to 9 also. As soon as the compiling procedure was
started and ended successful (in doing so no program code may be present) the array appears into the
solution explorer of the TwinCAT 3 development environment within the section PLC under "..Instance".
The following illustration shows extracts of the solution explorer on the right. As an example that linking of an
array variable to a set of oversampling process data is represented herewith:
Fig. 142: Representation of a created PLC array variable („aUI_Samples") to link with oversampling PDOs of
EL3773
Step 2b: Creation of a PLC variable via a free task
When a POU is not needed onto the particular system, a referenced variable could be applied via a free task
also. If a free task is not existing still yet, it can be created by a right-click to "Task" of the project within
SYSTEM with "Add New Item...".
114 Version: 1.1 EL3783