Reset input

Edge-triggered input for resetting error messages if the cause of the error is no longer present.

Data type: BOOL
Initial value: FALSE

The Reset input supports manual resetting of an active start-up or restart inhibit by the operator (see EN ISO 13849-1).

Note
Resetting does not occur with a negative (falling) edge, as specified by standard EN ISO 13849-1, but with a positive (rising) edge.
To implement the reset with a falling edge (with regard to the mandatory acceptance procedure), use the safety-related function block SF_Reset.

Additional measures, e.g., an additional function stop, can be taken to reduce the risk of an unintended start-up.

Connection: With the signal of a reset button connected to the Safety PLC (value TRUE or FALSE). Constant TRUE or FALSE values are not permitted.

Value	Description
FALSE	Error resetting and removal of an active start-up inhibit are not requested.
Edge FALSE > TRUE	Error resetting and removal of an active start-up inhibit are requested. The function block performs internal edge monitoring for the Reset input. A reset is only executed on a positive signal edge. A further static TRUE signal after a positive signal edge has no effect.

Resetting the function block by means of a positive signal edge at the Reset input can cause the S_Mode0Sel..S_Mode7Sel output to switch to SAFETRUE immediately (depending on the status of the other inputs).

WARNING

Unintended start-up

Include in your risk analysis the impact of the reset 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 established to help avoid hazardous situations when resetting.
Do not enter the zone of operation when resetting.
Ensure that no other persons can access the zone of operation when resetting.
Use appropriate safety interlocks where personnel and/or equipment hazards exist.

Note
If the function block is expecting a positive edge for resetting (inhibit is active or an error state applies), a static TRUE signal at Reset will be regarded as an error. In such cases, switch Reset to FALSE to exit the error state.