R_TRIG

Provided by standard.lib.

The function block R_TRIG detects a rising edge.

FUNCTION_BLOCK R_TRIG

VAR_INPUT

CLK : BOOL;

END_VAR

VAR_OUTPUT

Q : BOOL;

END_VAR

VAR

M : BOOL := FALSE;

END_VAR

Q := CLK AND NOT M;

M := CLK;

The output Q and the help variable M will remain FALSE as long as the input variable CLK is FALSE. As soon as CLK returns TRUE, Q will first return TRUE, then M will be set to TRUE. This means each time the function is called up, Q will return FALSE until CLK has falling edge followed by an rising edge.

Declaration example

RTRIGInst : R_TRIG ;

Example in IL

CAL RTRIGInst(CLK := VarBOOL1)

LD  RTRIGInst.Q

ST  VarBOOL2

Example in FBD

Example in ST

RTRIGInst(CLK:= VarBOOL1);

VarBOOL2 := RTRIGInst.Q;