Coil Types (LD Code Objects)

Contacts and coils are basic elements of LD networks.

In PLCnext Engineer, they can be used in FBD/LD, NOLD, SNOLD and SFC code worksheets.

A coil copies the state of the element on its left to the element on its right without modification. It stores an appropriate function of the state or transition of the left link into the associated Boolean variable (shown above the coil). The type of the coil is represented with the symbol of its modifier.

Coil The Boolean value is copied from the left to the right and to the associated variable.

Negated coil The Boolean value is copied from the left to the right. The negated Boolean value is copied to the associated variable.

SET coil The Boolean value is copied from the left to the right. The associated variable is set if the left link is TRUE.

RESET coil The Boolean value is copied from the left to the right. The associated variable is reset if the left link is TRUE.

Positive transition-sensing coil The positive transition-sensing coil compares the state of the left element during the current ladder rung evaluation to its state during the previous ladder rung evaluation. The value TRUE is copied from the left to the right and written to the associated data item when the last state of the left element was FALSE and the current state is TRUE.
This object is not supported in safety-related code (SNOLD).

Negative transition-sensing coil The negative transition-sensing coil compares the state of the left element during the current ladder rung evaluation to its state during the previous ladder rung evaluation. The value TRUE is copied from the left to the right and written to the associated data item when the last state of the left element was TRUE and the current state is FALSE.
This object is not supported in safety-related code (SNOLD).

Further Info
For a description of the objects that are common to all graphical programming languages, for example, connectors, jumps, returns etc. refer to the topic "Constants, Jumps/Labels, Returns, Connectors".

	Coil	The Boolean value is copied from the left to the right and to the associated variable.
	Negated coil	The Boolean value is copied from the left to the right. The negated Boolean value is copied to the associated variable.
	SET coil	The Boolean value is copied from the left to the right. The associated variable is set if the left link is TRUE.
	RESET coil	The Boolean value is copied from the left to the right. The associated variable is reset if the left link is TRUE.
	Positive transition-sensing coil	The positive transition-sensing coil compares the state of the left element during the current ladder rung evaluation to its state during the previous ladder rung evaluation. The value TRUE is copied from the left to the right and written to the associated data item when the last state of the left element was FALSE and the current state is TRUE. This object is not supported in safety-related code (SNOLD).
	Negative transition-sensing coil	The negative transition-sensing coil compares the state of the left element during the current ladder rung evaluation to its state during the previous ladder rung evaluation. The value TRUE is copied from the left to the right and written to the associated data item when the last state of the left element was TRUE and the current state is FALSE. This object is not supported in safety-related code (SNOLD).