SR / SR_S - Set dominant

This bistable function block realizes a prior set of the output Q1. If the input SET1 = TRUE, the output Q1 is set. Q1 remains set even if SET becomes FALSE. Q1 is reset, if RESET = TRUE. If SET1 and RESET1 are TRUE, Q1 is set by SET1 to TRUE. If the function block is called for the first time, Q1 is FALSE.

The function block is available as standard function block SR and safety-related function block SR_S.

SR

Parameter	Data types	Description
SET1	BOOL	If TRUE, Q1 is set dominant
RESET	BOOL	If TRUE, Q1 is reset
Q1	BOOL	Output

SR_S

Parameter	Data types	Description
SET1	SAFEBOOL	If TRUE, Q1 is set dominant
RESET	SAFEBOOL	If TRUE, Q1 is reset
Q1	SAFEBOOL	Output

NOTE:

Function blocks have to be instantiated. Like variables, instances have to be declared before they can be inserted in a code body. Instances must be unique within the POU. In the following example, the instance name 'SR_S_1' is used for the SR_S FB.

Example for a safety-related function block declaration SR_S

The following example realizes a simple blind control: Blinds are raised at wind speeds > 180.

Variables declarations in this example

NOTE:

If you want to use the standard function block SR in your code worksheet, you have to select the data type 'SR' for the function block instance in the local variables worksheet. Accordingly, the data types 'BOOL' and 'INT' must be used instead of 'SAFEBOOL' and 'SAFEINT'.