Delta AX-3 Series, Руководство по эксплуатации

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C h a p t e r 7 M o t i o n C o n t r o l B a s i c S e t t i n g s & O p e r a t i o n
7 - 4 5
7_
7.6 Motion Control Programming
7.6.1 Motion Control Program
Before programming in DIADesigner-AX, please take the following description as reference.
7.6.1.1 Program Architecture and Types in DIADesigner-AX
In the classic architecture, a source code for a PLC is composed of procedures including subroutines. When the
size of a program becomes larger, maintenance and debugging also becomes a huge burden. Under the IEC
61131-3 architecture, a program is divided into several units according to the functions or characteristics which
makes developing and maintaining much easier. Since POU are modularized, different POU can be developed by
different designers to enhance distribution of professional manpower and project execution
There are three types of POUs: program (PROG), function block (FB) and function (FC).
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Program (PROG):
The program type plays a major process role in a PLC program. The execution is assigned by Task which
includes specific scan cycle or interrupt subroutines and provides scan order arrangement for programs in the
Task list. Besides, a POU of the program type can call a function block (FB).
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Function block (FB):
A static symbol can be declared in a function block (FB). As a result, the value of the symbol after an operation
can be retained. Owing to the fact that the operation is performed on the value memorized in the function block
and an input value, the output values may be different even if the input values are the same.
Besides, a function block can call another function block.The function block (FB) type is similar to subroutines.
The FB process requires suitable parameters and can only execute once called by a program.
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Function (FC):
Function (FC) is used to return back operation results. Contrary to FBs, it have no memory and can only return a
single value. Since an FC does not have any memory of its own, it cannot call a function block but a function.
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Tasks
Each program POU needs to assign a Task that determines the order for program execution or start.
The programming structure characteristic of IEC 61131-3 is that a program can be divided into several
independent POUs. When POUs are compiled, they are rearranged and combined into an execution code for
scanning. The new combination order of POUs are based on the assigned Tasks.
Below are types of tasks:
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Cyclic: Assigned POU sets interval time for per scan.
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Event: When Bool variable is set from False to True, a scan execution is performed.
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External: When external triggers to send a signal, a corresponding POU is executed.
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Freewheeling: Assigned POU performs scan automatically in a continuous loop when the previous scan has
been completed.
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Status: When Bool variable is set from False to True, a scan cycle is executed.
Please refer to section 4.4.1 for the details of task operating process.