Supplementary Conditions For Link Axes - Siemens SINUMERIK 840D sl Function Manual

B3: Several operator panels connected to several NCUs, distributed systems - only 840D sl
2.6 Link axes
2.6.4

Supplementary conditions for link axes

Output of alarms from position controller or drive
Axis alarms are always output on the NCU which is producing the interpolation value. If an
alarm is generated for a link axis by the position controller, then the alarm is transferred to
the NCU which is currently processing the interpolation.
On the assumption that axis alarms which cause the NCK-Ready relay to drop out (Nck-
NoReady) are attributable to faults on the drive bus, the alarm is also output on the NCU on
which the axis or the drive bus is physically operated. The reaction "Ready relay dropout" is
only activated on this NCU.
Output of alarms following EMERGENCY STOP
If an EMERGENCY OFF request is activated by the PLC on an NCU, all axes physically
connected to drives on this NCU are switched to follow-up mode. This means that: even
axes which are being interpolated by a different NCU are also switched to follow-up. Since
this status prevents any further constructive machining operations on the other NCUs, an
additional alarm is generated which is designed to stop all axis motion instantaneously.
This additional alarm must be acknowledged by an NC reset. If the original alarm is still
active at this time, then the additional alarm can be successfully reset, but another alarm
(self-clearing) is then produced which prevents axis motion or a new program start until the
original alarm has been reset.
Output of alarms with alarm reaction NCK-NoReady
If a serious alarm resulting in dropout of the NCK-Ready relay is activated on an NCU, then
the effects of the alarm will apply to all other NCUs which are addressing an axis via link
communication on the first NCU. An additional alarm which causes all other axes to stop
instantaneously is activated on each of the other NCUs.
For alarm acknowledgement, see EMERGENCY STOP.
Compensation
The following compensations are not available for link axes:
● Sag compensation (CEC)
● Leadscrew error compensation (LEC)
● Quadrant error compensation (QEC)
Switching off grouped NCUs
If an NCU in a link grouping is switched off or restarted by an NCK reset, all the other NCUs
in the link grouping will also be affected. An alarm is generated on these and the process
currently taking place is aborted.
See "Configuration of a link grouping (Page 174)".
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Function Manual, 09/2009, 6FC5397-1BP20-0BA0
Extended Functions