Program Unit - Mitsubishi Electric MELSEC iQ-F Series Programming Manual

Program unit

FBD unit
Units constituting FBD/LD program are shown below.
Unit Symbol
Variable
Constant
Function (FUN)
Function Block (FB)
■The data type of a constant unit
In the case of a constant unit, the data type of the constant value is not determined at the time when the constant value is
input. The data type is determined when the constant unit and an FBD unit are connected over a connecting wire. The data
type of the constant value is the same data type as the FBD unit at the destination of the connecting wire.
Ex.
When 1 is input as a constant value
The data type can be a BOOL type, a WORD type, a DWORD type, an INT type, a DINT type, or a REAL type. So, the data
type is not determined. When the constant unit and an FBD unit are connected over a connecting wire, the data type becomes
the data type at the input point of the unit at the destination of the connection.
1
(1)
1
(2)
■Automatic conversion of data types
The data type of an element may be automatically converted when it is connected to another element of a different data type.
To avoid the deletion of the data during the type conversion, only conversion from smaller type to larger type is performed.
Automatic conversion of data type in the FBD/LD language behaves in the same way as that in the ST language. For details,
refer to the following.
Page 51 Automatic conversion of data types
Description
A variable is used to store each value (data). The data type of a variable should be a certain type.
Only the value (data) of the data type is stored.
You can specify a label or a device to a variable.
The constant specified is output.
Executes a function.
• How to create functions (GX Works3 Operating Manual)
• Standard function (MELSEC iQ-F FX5 Programming Manual (Instructions, Standard
Functions/Function Blocks))
Executes a function block.
• How to create function blocks (GX Works3 Operating Manual)
• Standard function blocks (MELSEC iQ-F FX5 Programming Manual (Instructions, Standard
Functions/Function Blocks))
• Module function blocks (MELSEC iQ-F FX5 CPU Module Function Block Reference)
INT_TO_REAL
IN
(3)
(1) The data type is not determined.
(2) INT type
(3) INT type
7 FBD/LD LANGUAGE
7.1 Configuration
7
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