Mitsubishi Electric FX2N-32CAN, Руководство по обучению

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10 Data Unit Types (DUT)
The following example illustrates the operation of DUT ( D ata U nit T ypes).
The previous “Motor Control” example will be used to illustrate the procedures for creating and
using DUT’s.
User defined Data Unit Types (DUT), can be created. This can be useful for programs which
contain common parts, for example; the control of a number of identical ‘Star Delta’ motor start-
ers. Therefore a Data Unit Type, called ‘SD’ can be created, composing patterns of different ele-
ments, i.e. INT, BOOL etc.
When completing a global variable list, identifiers of type SD can be used. This means that the
predefined group called ‘SD’ can be used with the elements defined as required for each Motor
Control, thus reducing design time and allowing re-use of the DUT together with Function
Blocks.
If an element called START exists in type “SD,” then it can be reused for each ‘Star Delta’ Motor
Control instance when declared in the GVL; STAR_DELTA1.START, STAR_DELTA2.START
etc.
This means for one declaration, many derivatives can be used. One particular use for this proce-
dure is in the interface to Tag Groups in SCADA systems. This can keep communication cycles
fast and efficient by utilising shorter and sequential data transactions, instead of multiple frag-
mented data requests to and from the PLC.
Data Unit Types (DUT)
Training Manual GX IEC Developer 10 - 1