SF_Equivalent (FB)

FUNCTION_BLOCK SF_Equivalent

This function block converts two equivalent SAFEBOOL inputs (both NO or NC) to one SAFEBOOL output, includ-ing discrepancy time monitoring.

This function block should not be used stand-alone since it has no restart interlock. It is required to connect the output to other safety related functionalities.

Function block according to PLCopen, Technical Committee 5: Safety Software (Technical Specification), Part 1: Concepts and Function Blocks, Version 2.01 (2020-2)

InOut:

Scope	Name	Type	Initial	Comment
Input	Activate	BOOL	FALSE	Activation of the FB.
	S_ChannelA	BOOL	FALSE	Input A for logical connection.
	S_ChannelB	BOOL	FALSE	Input B for logical connection.
	DiscrepancyTime	TIME	TIME#0ms	Maximum monitoring time for discrepancy status of both inputs.
Output	Ready	BOOL	FALSE	Activation of the FB. TRUE indicates that the FB is activated and the outputs results are valid, FALSE the FB is not active and the program is not executed.
	S_EquivalentOut	BOOL	FALSE	Safety related output
	SafetyDemand	BOOL	FALSE	Output indicating that the FB is active and the primary safety function is demanded (e.g. related to the safety functionality).
	Error	BOOL	FALSE	Error flag
	DiagCode	WORD	0	Diagnostic register