LF: Coils

A Coil represents a result or expression of an action. A coil turns ON when the preceding net conditions are ON, allowing power flow to reach the coil from the net. If the preceding net conditions are OFF, a coil turns OFF.

Each contact condition is evaluated in a net to determine the coil (result or expression) condition.

Note

Do not energize a coil more than once in a program.

Direct Coil

A Direct Coil turns ON when the preceding net conditions are ON, allowing power flow to reach the coil from the net.

If the preceding net conditions are OFF, a direct coil turns OFF.

The coil can represent an external output device (for example: alarm bell) or an application element such as an HMI button.

Inverted Coil

An Inverted Coil turns OFF when the preceding net conditions are ON, allowing power flow to reach the coil from the net.  

If the preceding net conditions are OFF, an inverted coil turns ON.

The coil can represent an external output device (for example: alarm bell) or to an internal system element.

Reset Coil

A Reset Coil turns a set coil OFF (unlatches), when the preceding net conditions are ON, allowing power flow to reach the reset coil from the net. 

 

Note

Once a set coil is turned ON, it stays ON, independent of the original set condition, until a reset coil linked to the same address resets (unlatches) the coil condition.

Do not use a set coil without a reset coil in a program.

Set Coil

A Set Coil separates the coil from the action or condition that energized the coil. Once energized, a set coil's result is no longer dependent on the action that energized it. 

A set coil stays energized (latched) until its condition is reset (unlatched) by a reset coil.

An example of a set coil is an overhead light. When you turn on a light, it stays lit until you turn it off (reset or unlatch it) or the light bulb burns out. You do not have to hold the light switch to keep the light on.

An example of a coil that you do not want to be set ( latched) is a car horn. You expect it to toot only when you press on the horn button and you expect it to stop when you stop pressing on the horn button.

Do not use a set coil without a reset coil in a program.

Toggle Coil

A Toggle Coil changes its state when it is activated.  

An example of a toggled coil is an light switch. When you turn on a light, it stays lit until you toggle it; it then turns off. The light stays off until you toggle it back on.

Positive Transition Coil

A Positive Transition Coil turns ON for a single program cycle, if the RLO changes from 0 (OFF) in the previous scan to 1 (ON) in the current scan.

Negative Transition Coil

A Negative Transition Coil turns ON for a single program cycle, if the RLO changes from 1 (ON) in the previous scan to 0 (OFF) in the current scan.

Related Topics

RLO

LF: Contacts

LF: Reset Numeric

LF: Store Integer

LF: Compare Structs