Siemens SINUMERIK 840D sl Operating Manual page 814

Alarm, error and system messages
25.1 Displaying alarms
...
Acknowledgement symbols
Symbol
...
814
4. Position the cursor on an alarm.
5. Press the key that is specified as acknowledgement symbol to delete
the alarm.
- OR -
Press the "Delete HMI alarm" softkey to cancel an HMI alarm.
- OR -
Press the "Acknowledge alarm" softkey to delete a PLC alarm of the SQ
type (alarm number as of 800000).
The softkeys are activated when the cursor is on the corresponding
alarm.
Meaning
Turn the unit off and back on (main switch), or press NCK POWER ON.
Press the <RESET> key.
Press the <ALARM CANCEL> key.
- OR -
Press the "Acknowl. HMI alarm" softkey.
Press the key provided by the manufacturer.
Machine manufacturer
Please refer to the machine manufacturer's specifications.
Operating Manual, 02/2012, 6FC5398-8CP40-3BA0
Turning