Ethercat Symbols; Symbols; Application Of Symbols; Classes - Delta AH Series Operation Manual

AH Mo t io n C on tr o ll er – O p er a t io n M a nu a l

5.3. EtherCAT Symbols

The EtherCAT symbols are used to read states of EtherCAT slave. The symbols can be seen from the EtherCAT symbol
table in the ISPSoft software.
EtherCAT Symbol
eCAT_Dis.SlaveAddress[...]
eCAT_Dis.Count

5.4. Symbols

During the process of developing a traditional program for a PLC, it generally takes much time to manage device
addresses. Besides, managing or debugging the program in a big project is a burden on users. As a result, the concept of
symbols* in a high-level programming language is introduced by IEC 61131-3. A device in a PLC can be represented by a
symbol, and a device can be automatically assigned to a symbol. In this way, the time to assign devices is saved, the
program is more readable, and the efficiency of developing a program increases.
*Note: Variables in ISPSoft are called symbols. As a result, variables are the same as symbols in terms of meaning in this
manual.

5.4.1 Application of Symbols

A symbol has to be declared before it is used. There are two types of symbols. They are global symbols and local symbols.
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The global symbols in a project can be used in all the POUs* in the project, and the local symbols in a project can only be
used in the POU in which the local symbols are declared. Besides, the identifier of a local symbol in a POU can be the
same as the identifier of a local symbol in another POU. However, if this local symbol identifier is the same as a global
symbol identifier, the system will automatically regard it as a local symbol.
*Note: For further explanations regarding a POU, refer for ISPSoft User Manual.

5.4.2 Classes

Symbols can be categorized into four classes. The features of the four classes are described below.
 VAR－General symbol
The symbols of this class are for general operations only. The significance of a symbol of this class depends on the
data type of the symbol.
 INPUT－Symbol used as an input pin of a function block
A symbol of this class is used as an input pin of a function block. It can only be declared in the function block. If a
function block is called, the symbols of this class can receive the input values sent by the caller. In a ladder diagram,
INPUTs are put at the left sides of function blocks with pins receiving the input values sent by the caller.
 OUTPUT－Symbol used as an output pin of a function block
A symbol of this class is used as an output pin of a function block. It can only be declared in a function block. After the
execution of a function block is complete, the operation results will be sent to the caller through the symbols of this
5 - 1 6
Data type Description
The EtherCAT slave address
that disconnected
WORD[199]
(n=0~198)
The number of EtherCAT
WORD slave address that
disconnected
Default
Range
settings
0~9999 0
16
0~（2 -1） 0