Siemens SINUMERIK 840D sl Function Manual page 180

Several Operator Panels on Several NCUs, Distributed Systems (B3)
Communication in link grouping
Figure 2-28
Configuration limit
The diagram above illustrates how the communication overhead grows as the number of
NCUs increases.
Curve trace A:
Time required for the exchange of link variables/machine data information and the lead link
axis information (one lead link axis) between the NCU giving the master value and other
NCUs that interpolate the following axes as a function of the leading axis (lead link axis).
Curve trace B:
Time required for the exchange of link variables/machine data information between the NCU
giving the master value and other NCUs that interpolate the following axes as a function of
the leading axis (lead link axis).
180
Increase in communication time of the number of NCUs connected via the link (for
scaling refer to Interdependencies)
Function Manual, 03/2009, 6FC5397-1BP10-4BA0
Extended Functions