7.1.1 SR

Function

SR is called set priority standard bistable element, that is, set priority

LD graphics

Parameter description

Interface variables	Declaration	Data type	Description
S1	Var_Input	BOOL	Set
R	Var_Input	BOOL	Reset
Q1	Var_Output	BOOL	Operand signal status

Corresponding syntax:

• Q1 = S1 OR (NOT R AND Q1)
• When the S1 and R signals are both TRUE, the operand signal status is set to "1";
• When the S1 signal is TRUE and the R signal is FALSE, the operand signal status is set to "1";
• When the S1 and R signals are both FALSE, the operand signal status remains unchanged;
• When the S1 signal is FALSE and the R signal is TRUE, the operand signal status is reset to "0"

warning

Function block usage requires global declaration of an instance

Example

• LD example is shown in the animation below

• ST example is shown in the following code:

SR_1(S1:=IN1,R:=IN2,Q1=>OUT);
IF OUT THEN
    iVar:=1;
    ELSE
        iVar:=0;
END_IF;