Siemens SINUMERIK 840D sl Commissioning Manual page 191

SIM/NCK twist button
The switch positions of the SIM/NCK switch have the following meaning:
Switch position
PLC twist button
The switch positions of the PLC switch have the same meaning as in a SIMATIC S7-CPU:
Switch position
NCU Operating System (IM7)
Commissioning Manual, 07/2007, 6FC5397-1DP10-2BA0
Operating mode of the NCK
0 Normal boot-up NCK
1 NCK boot-up with default values (= memory reset)
2 The NCK (and PLC) starts up with the data that was saved at the last
shutdown.
7 Debug mode (NCK is not started.)
8 IP address of the NCU is displayed on the seven-segment display.
All others Not relevant
Operating mode of the PLC
0 RUN
1 RUN (protected mode)
2 STOP
3 Memory reset (MRES)
All others Not relevant
Commissioning a System
1.4 Meaning of switch positions
9