Siemens SINUMERIK 840D sl Commissioning Manual page 37

The NCU is in the following state after an error-free boot-up:
● The NC is in cyclic operation.
● The static memory of the NC is deleted.
● The machine data is preassigned standard values.
Alternatives
A PLC general reset can be performed with or without power-on reset. Depending on this,
various states are obtained for the PLC program.
General PLC reset without a power-on reset
Carry out the following actions to execute a general PLC reset without a power-on reset:
1. Turn the PLC mode selector switch on the front of the NCU to position "2" (STOP).
Effect:
– The PLC goes into the "STOP" mode.
– The "STOP" LED illuminates.
2. Turn the PLC mode selector switch to position "3" (MRES)
Effect:
– The "STOP" LED goes dark and after approx. three seconds illuminates again.
3. Within approx. three seconds, turn the PLC mode selector switch to the positions "2" → "3"
→ "2"
Effect:
– The "STOP" LED first flashes with about 2 Hz and then illuminates continuously.
4. Turn the PLC mode selector switch back to the "0" position.
Effect:
– The "STOP" LED extinguishes.
– The "RUN" LED illuminates.
The general reset places the PLC in a defined state:
● The PLC is in cyclic operation.
● The time of day and the operating hours counter have not been reset.
● The diagnostics buffer and the MPI parameters have not been reset.
Note
For the general reset without power-on reset, the most recently loaded blocks from the PLC
program are reimported.
CNC Commissioning: NC, PLC, Drive
Commissioning Manual, 12/2019, A5E48312804B AA
Requirements for commissioning
3.4 Power-On and boot-up
37