Siemens SINUMERIK 840D sl Function Manual page 84

B3: Distributed systems - 840D sl only
3.2 NCU link
Data transfer
Depending on the active functions, the following cyclic and non-cyclical data transmissions
occur between the NCUs involved with the link communication:
● High-priority, cyclic data transfer:
– Setpoints, actual values and status signals of the axes
– NCU status signals
● High-priority, non-cyclic, non-displaceable data transfer:
– Non-safety-related data as part of the Safety Integrated function
– States of the container axes during an axis container rotation
● Low-priority, non-cyclic, displaceable data transfer (listed in order of decreasing priority):
– Link variables
– Warm restart requirements
– Activation of axis container rotations
– Changes in NCU-global machine and setting data
– Activation of the axial machine data for link axes
– Alarms
Displacement
If for low-priority, non-cyclic, displaceable data transmission not all requirements can be sent
in a single interpolator cycle, the request with higher priority displaces that with a lower priority.
This will then be sent later.
Quantity structure: NCU 7x0.3 PN
As standard, a maximum of three NCUs can be interconnected to form a link group.
Note
For a specific project, on request to your local regional Siemens representative an NCU-link
group with more than three NCUs is possible. Without project-specific supplements, more than
three NCUs are rejected with Alarm 380020.
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Function Manual, 10/2015, 6FC5397-1BP40-5BA3
Extended Functions