SR

Set/reset

The function block SR (set/reset) allows you to both set and reset an output.

Parameters

Input

S1 (BOOL)

Set

The output Q1 is set for each rising edge at S1

R (BOOL)

Reset

The output Q1 is reset for each rising edge detected at R, except when S1 is set (see time chart)

Output

Q1 (BOOL)

Set or reset depending on inputs

set if a rising edge is detected at S1
reset if a rising edge is detected at R if S1 is not set.
set if a rising edge is detected at both inputs (S1 and R).
Upon initialising, Q1 always has the status zero (reset).

Time chart

Example

POU header

All input and output variables used for programming this function have been declared in the POU header. The same POU header is used for all programming languages.

	VAR
		copy_name: SR;
		set: BOOL:=FALSE;
			(*output_value is set for each
rising edge at set_input,
if reset_input is not set*)
		reset: BOOL:=FALSE;
			(*output_value is reset for each
rising edge at reset_input*)
		signal_output: BOOL:=FALSE;
	END_VAR

LD body

If set is set (status = TRUE), signal_output will be set. If only reset is set, the signal_output will be reset (status = FALSE). If both set and reset are set, signal_output will be set.

BODY
    WORKSPACE
        NETWORK_LIST_TYPE := NWTYPELD ;
        ACTIVE_NETWORK := 0 ;
    END_WORKSPACE
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 5 ;
        NETWORK_BODY
B(B_VAROUT,,signal_output,13,2,15,4,);
B(B_CONTACT,,set,3,1,5,3,);
B(B_CONTACT,,reset,3,3,5,5,);
B(B_FB,SR!,copy_name,8,1,13,5,,?BS1?BR?AQ1);
L(1,2,3,2);
L(1,4,3,4);
L(5,4,8,4);
L(5,2,5,3);
L(5,3,8,3);
L(1,0,1,5);
        END_NETWORK_BODY
    END_NET_WORK
END_BODY

ST body

copy_name( SET:= set, RESET:= reset);
        signal_output:= signal_output;