7 FBD/LD LANGUAGE
7.1 Configuration
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7
■The operation of a return unit
A return unit operates differently depending on whether a program, function, and/or function block used there.
If a return element is used in a macro-type function block, do not place two or more function block elements of the same
instance name.
A local label "_SYSTEM_RETURN" is automatically registered when a program using a return element is converted.
The local label "_SYSTEM_RETURN" has the following operational limitations:
*1 If the program is converted again after change or deletion, a new local label is registered.
■Connector unit
Use a connector element to place the program within the display area or print area of the FBD/LD editor.
Connecting wire
This is the wire to connect the connecting points between FBD unit, LD unit, and common unit.
After units are connected, the data is transferred from the left end to the right end. The data types of the connected units need
to be the same.
Connecting point
This is a terminal point to use a connecting wire to connect FBD unit, LD unit, and common unit.
The point on the left side of each unit is the input side, while the point on the right side represents the output side.
The connecting point is hidden after connecting a wire.
Program unit to use
Program The execution of the program unit is terminated.
Function The function is terminated, and the step goes back to the one next to the instruction that has called the function.
Function block The function block is terminated, and the step goes back to the one next to the instruction that has called the function
block.
Operation on the label automatically registered Permitted/Prohibited
Changing the label name Prohibited
*1
Changing the data type Prohibited
Changing the class Prohibited
Deleting the label Prohibited
*1
Changing the line of registration Permitted
Unit Input connecting
point
Output connecting
point
Unit Input connecting
point
Output connecting
point
Contact Coil
Variable Constant
Function
The return value is not
shown on a function.
Function Block
CONNECTOR
Var1 Var2 Var3 Var4 Var5
CONNECTOR
Var6 Var7 Var8
Coil1
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