[RQ11.4] The device a SafetyConsumer is running on shall be able to indicate if SAPI.OperatorAckRequested is enabled. This can be done for example by an indicator LED or using an HMI.
[RQ11.5] If an LED is used for indication, it shall blink in green color with frequency of 0.5 Hz whenever the output SAPI.OperatorAckRequested is true of at least one of the SafetyConsumers running on the device.
The message shown on an HMI is application specific. For instance, the text “Machine has stopped for safety reasons. For restart, please check for obstacles and press the green button.”