SF_Antivalent (FB)¶

FUNCTION_BLOCK SF_Antivalent

This function block converts two antivalent SAFEBOOL inputs (NO/NC pair) to one SAFEBOOL output with discrepancy time monitoring.
This FB 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_ChannelNC`	`BOOL`	FALSE	Input for NC (Normally Closed) connection. FALSE: NC contact open, TRUE: NC contact closed.
	`S_ChannelNO`	`BOOL`	FALSE	Input for NO (Normally Open) connection. FALSE: NO contact open, TRUE: NO contact closed.
	`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_AntivalentOut`	`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