S_SafeControl input

This state-controlled input evaluates the status of an upstream safety-related function (requested or not requested).

Data type: SAFEBOOL
Initial value: SAFEFALSE

Connection: Connect this input directly or via other safety-related functions to the enable signal of an upstream safety-related function block, which evaluates a piece of safety equipment connected to the Safety PLC and signals the status (e.g., SF_EmergencyStop for evaluating an emergency-stop control device). Constant SAFETRUE or SAFEFALSE values are not permitted.

If the function block is activated (Activate = TRUE), the possible values at this input lead to the following function block behavior:

Value Description

SAFETRUE The upstream safety-related function has not triggered (normal operation).
Refer to the warning below this table.

SAFEFALSE The upstream safety-related function has triggered.
The S_OutControl output is switched to SAFEFALSE.

Value	Description
SAFETRUE	The upstream safety-related function has not triggered (normal operation). Refer to the warning below this table.
SAFEFALSE	The upstream safety-related function has triggered. The S_OutControl output is switched to SAFEFALSE.

If no start-up inhibit is specified for the function block and no additional operation stop of the standard controller is specified with StaticControl = TRUE, the SAFETRUE status at the S_SafeControl input can cause the S_OutControl output to switch to SAFETRUE immediately.

WARNING

Unintended start-up

If no start-up inhibit and no additional operation stop of the standard controller (StaticControl = TRUE) is specified:

Be sure that your risk analysis includes an evaluation for the state change at the S_OutControl output after applying SAFETRUE to the S_SafeControl input.

Make certain that appropriate procedures and measures (according to applicable sector standards) have been established to help avoid hazardous situations when applying SAFETRUE to the S_SafeControl input.

Use appropriate safety interlocks where personnel and/or equipment hazards exist.

Note
To control the restart behavior of the function block following a signal change from SAFEFALSE to SAFETRUE at the S_SafeControl input (once the request for the safety-related function has been removed), you can specify a restart inhibit at S_AutoReset.