S_AutoReset input

This input is used to specify the restart inhibit after the SAFETRUE signal returns at the S_GuardSwitch1/2 input (in other words, once the safety-related function is no longer requested).

When a restart inhibit is active, all safety-related outputs of the function block are in the defined safe state. This ensures that a machine/system cannot be restarted inadvertently. If a restart inhibit has been specified, a reset signal is required to remove the inhibit and enable the machine/system to function.

Data type: SAFEBOOL
Initial value: SAFEFALSE

Connection: Connect this input to a variable or constant.

If Activate = TRUE, the possible values at S_AutoReset lead to the following function block behavior:

Value Description

SAFETRUE No restart inhibit for the function block when the safety-related function is no longer requested.
If no restart inhibit has been specified for the function block, the SAFETRUE status at the S_GuardSwitch1/2 input can cause the S_GuardOut output to immediately switch to SAFETRUE.1

SAFEFALSE Active restart inhibit for the function block after the SAFETRUE signal returns at the S_GuardSwitch1/2 input (in other words, once the safety-related function is no longer requested).
The restart inhibit must be manually removed by means of a reset signal (positive signal edge) at the Reset input.2

Value	Description
SAFETRUE	No restart inhibit for the function block when the safety-related function is no longer requested. If no restart inhibit has been specified for the function block, the SAFETRUE status at the S_GuardSwitch1/2 input can cause the S_GuardOut output to immediately switch to SAFETRUE.1
SAFEFALSE	Active restart inhibit for the function block after the SAFETRUE signal returns at the S_GuardSwitch1/2 input (in other words, once the safety-related function is no longer requested). The restart inhibit must be manually removed by means of a reset signal (positive signal edge) at the Reset input.2

1 If no restart inhibit is specified, observe the following:

WARNUNG

Unintended start-up

Be sure that your risk analysis includes an evaluation for the state change at the S_GuardOut output after applying SAFETRUE to the S_GuardSwitch1/2 input.

Make certain that appropriate procedures and measures (according to applicable sector standards) have been taken to help avoid hazardous situations when applying SAFETRUE to the S_GuardSwitch1/2 input.

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

2 After the restart inhibit has been removed, the status at the S_GuardOut output can switch from SAFEFALSE to SAFETRUE immediately if there is a valid signal combination at the other inputs.

WARNUNG

Unintended start-up

Verify the impact of removing the restart inhibit by means of a positive signal edge at the Reset input.

Make certain that appropriate procedures and measures (according to applicable sector standards) have been taken to help avoid hazardous situations when removing the restart inhibit.

Do not enter the zone of operation when removing the restart inhibit.

Ensure that no other persons can access the zone of operation when removing the restart inhibit.

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

WARNUNG

Non-conformance to safety function requirements

Verify that a restart inhibit facility is implemented in your safety-related network if required for your specific safety-related function according to the relevant standards.

WARNUNG

Unintended start-up

Validate the behavior of the function block and the safety-related network as a whole and thoroughly test the application.