Siemens SINUMERIK 840Di Function Manual page 925

Note
On the SINUMERIK 810D or 840D, SIMATIC subrack 0 is integrated in the NC. The
following components are plugged into this subrack:
- Slot 2: The integrated PLC (PLC 314 or PLC 315-2DP)
- Slot 3: An IM 360
- Slot 4: The FM NCU
With PLC 314, NC software version 3.5 and higher, the FM NCU must also be defined if
further MPI (C bus) devices are included in subrack 1 to subrack 3 (e.g., FM modules with C
bus connection). The properties of the FM NCU must not be changed, as process interrupts
(e.g. auxiliary functions) of the NCU may, in this case, no longer function.
Fig. 2-1 Hardware configuration of row 0 on 810D, 840D
Power Line Basic PLC Program (P3)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
2.3 Starting up hardware configuration of PLC CPUs
Detailed description
2-13