Siemens SINUMERIK 804D sl Commissioning Manual page 275

Figure 15-6
PLC status
The PLC always starts up in RESTART mode, i.e. the PLC operating system runs OB100
after initialization and starts cyclic operation at the beginning of OB1. There is no re-entry at
the point of interruption (e.g. on power failure).
Start-up behavior of the PLC
There are both remanent and non-remanent areas for the markers, times and counter. The
areas are continuous and are divided by a parameterizable limit, where the area with the
CNC Part 1 (NCK, PLC, drive)
Commissioning Manual, 11/2006, 6FC5397-2AP10-2BA0
PLC program structure
Fundamentals
15.5 PLC program
275