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7 FBD/LD language
7.1 Configuration
■The AND operation and OR operation of a contact symbol
A contact symbol executes an AND operation or an OR operation depending on the status of the connection of a circuit chart.
This is reflected in the operation result.
• In the case of a series connection (1), an AND operation is executed with the operation results so far. This will be the
operation result.
• In the case of a parallel connection (2), an OR operation is executed with the operation results so far. This will be the
operation result.
Common unit
This represents a common unit placed on the FBD/LD editor.
■Precautions for a jump unit
• If the timer of a coil that is ON is jumped over by using a jump unit, a normal measurement cannot be conducted.
• You can add a jump label on the top side (the execution is earlier) of a jump unit. In this case, create the program by
including a method to break the loop in order not to exceed the setting value of the watchdog timer.
• You can specify only a local label of a pointer type for a jump element and jump label. Pointer devices cannot be used.
• The pointer branch instruction (CJ) cannot be used. For jumping, use jump elements.
• Jumps to or from outside the program block cannot be executed. The following is a list of jump operations that cannot be
executed.
- Jumping to outside the program block
*1
- Jumping from outside the program block
*1
- Calling subroutine programs
- Called as subroutine programs
*1 Includes branches caused by the BREAK instruction.
Unit Symbol Description
Jump The execution processing is jumped over from a jump unit to a jump label. The portion that is
jumped over is not executed.
Whether a jump is made or not is controlled depending on the ON/OFF information to the jump unit.
ON: The execution processing is jumped over up to a jump label.
OFF: The execution processing is not jumped over but is executed.
Jump label This is the destination of a jump from a jump instruction in the same program. The processing is
executed from a program in the execution order after the jump label.
Connector This is used as a substitute of a connecting wire.
The processing moves on to the corresponding connector unit.
You can use one input connector or multiple input connectors for one output connector.
Return The processing after a return unit in the program is aborted. Use this when you want to prohibit the
execution of the processing of a program, function, or a function block after the return unit.
Whether the return processing is executed or not is controlled depending on the ON/OFF
information to the return unit.
ON: The return processing is executed.
OFF: The return processing is not executed, but the ordinary execution processing is executed.
Comment Use this to describe a comment.
(1) Series connection contact
(2) Parallel connection contact
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