[F_TRIG] Recognize negative edge and trigger impulse

Function block F_TRIG recognizes negative edge.

F_TRIG recognizes a negative edge.

Functioning

For a negative edge of input [In], output [Out] is set to [Out] = 1 for the program cycle.

Pins

Input

Description

Data type

Default value
Value range

In

Input

Boolean

0

0 - No
1 - Yes

 

Output

Description

Data type

Default value
Value range

Out

Output

Boolean

0

0 - Off
1 - On

Application

Function block F_TRIG is used for various kinds of control tasks such as to recognize the initial use of a button.

Process response
  • The old state of input value [In] is initialized with 0.

From the third process cycle, F_TRIG is processed with the value at the input, as the initialization type is identified only after the negative edge is recognized. The default value is issued during the first two process cycles.

info

Continuous signal [In] = 0 is not recognized as a negative slope on processing. Output [Out] remains = 0.