Siemens SINUMERIK 840D sl Function Manual page 42

Digital and analog NCK I/Os (A4)
1.2 NCK I/O via PLC
Fast analog NCK inputs
The fast analog inputs must be isochronous.
The assignment is defined by the machine data:
MD10384 $MN_HW_CLOCKED_MODULE_MASK
Figure 1-3
42
Signal flow for analog NCK inputs
Function Manual, 01/2008, 6FC5397-1BP10-3BA0
Extended Functions