Coils are basic graphic elements of the LD language. A coil is associated to a boolean variable written upon its graphic symbol. A coil performs a change of the associated variable according to the rung state on its left side.
Below are the possible coil symbols and how they change the rung state:
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Normal:
the associated variable is forced to the value of the rung state on
the left of the coil. |
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Negated:
the associated variable is forced to the negation of the rung state
on the left of the coil. |
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Set: the
associated variable is forced to TRUE if the rung state on the left
is TRUE. (no action if the rung state is FALSE) |
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Reset: the associated variable is forced to FALSE if the rung state on the left is TRUE. (no action if the rung state is FALSE) |
Note: When a contact or a coil is selected, You can press the SPACE bar to change its type (normal, negated, pulse...)
Important notes: Eventhough coils are commonly connected to a power rail on the right, the rung may be continued after a coil. The rung state is never changed by a coil symbol.