Specifications

5-14
5.2 Structured Ladder/FBD
5.2.2 Ladder symbols in structured ladder/FBD language
5.2.2 Ladder symbols in structured ladder/FBD language
The following table shows the ladder symbols that can be used in the structured ladder/FBD
language.
For details, refer to the following manual.
MELSEC-Q/L Structured Programming Manual (Common Instructions)
Table 5.2.2-1 Ladder symbols in the structured ladder/FBD language (1/2)
Element Ladder symbol Description
Normal
*1,*2
Turns ON when a specified device or label is ON.
Negation
*1,*2
Turns OFF when a specified device or label is OFF.
Rising edge
*1,*2,*3
Turns ON at the rising edge (OFF to ON) of a specified device or label.
Falling edge
*1,*2,*3
Turns ON at the falling edge (ON to OFF) of a specified device or
label.
Negated rising edge
*1,*2,*3
Turns ON when a specified device or label is OFF or ON, or at the
falling edge (ON to OFF) of a specified device or label.
Negated falling edge
*1,*2,*3
Turns ON when a specified device or label is OFF or ON, or at the
rising edge (OFF to ON) of a specified device or label.
Normal
*1
Outputs the operation result to a specified device or label.
Negation
*1
A specified device or label turns ON when the operation result turns
OFF.
Set
*1
A specified device or label turns ON when the operation result turns ON.
Once the device or label turns ON, it remains ON even when the
operation result turns OFF.
Reset
*1
A specified device or label turns OFF when the operation result turns
ON. If the operation result is OFF, the status of the device or label
does not change.
*1: Not applicable in FBD.
*2: A contact performs an AND operation or OR operation according to the connection of a
ladder block and reflects in the operation result.
• For a series connection, it performs an AND operation with the operation result up
to that point, and takes the resulting value as the operation result.
• For a parallel connection, it performs an OR operation with the operation result up
to that point, and takes the resulting value as the operation result.
*3: Supported with GX Works2 Version 1.15R or later.
For the confirmation method of the version of GX Works2, refer to the following manual.
GX Works2 Version 1 Operating Manual (Common)
( )
Series-connection contact
Parallel-connection contact