Attention

IronPLC can only run very simple programs. The steps described are accurate but many language features are not yet supported.

R_TRIG

Rising edge detector. Output Q is TRUE for one scan cycle when the input CLK transitions from FALSE to TRUE.

IEC 61131-3	Section 2.5.2.3.2
Support	Not yet supported

Inputs

Name	Type	Description
CLK	BOOL	Signal to monitor for rising edge

Outputs

Name	Type	Description
Q	BOOL	Edge output (TRUE for one scan on rising edge)

Behavior

The function block stores the previous value of CLK. When CLK transitions from FALSE to TRUE, the output Q is set to TRUE for one scan cycle. On all subsequent scans where CLK remains TRUE, Q is FALSE. When CLK is FALSE, Q is always FALSE.

Example

VAR
  edge1 : R_TRIG;
  button : BOOL;
  pressed : BOOL;
END_VAR

edge1(CLK := button);
pressed := edge1.Q;

See Also

• F_TRIG — falling edge detector