f_trig

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 Function Block - Falling pulse detection.

Inputs

Input

Data Type

Range

Unit

Default

Description

CLK

BOOL

 

 

 

Boolean signal.

Outputs

Output

Data Type

Range

Unit

Description

Q

BOOL

 

 

TRUE when the input changes from TRUE to FALSE.

Remarks

  • It is recommended to use declared instances of R_TRIG or F_TRIG function blocks.
    • This is to avoid contingencies during an Online Change.

Truth Table

CLK

CCLK (prev)

Q

0

0

0

0

1

1

1

0

0

1

1

0

FBD Language Example

FFLD Language Example

  • In the FFLD Language, ]P[ and ]N[ contacts can be used.

IL Language Example

(* MyTrigger is declared as an instance of F_TRIG function block *)
Op1: CAL MyTrigger (CLK)
LD  MyTrigger.Q
ST  Q

ST Language Example

(* MyTrigger is declared as an instance of F_TRIG function block. *)
MyTrigger (CLK);
Q := MyTrigger.Q;

See Also

r_trig