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

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 to
which the axis or the drive bus is physically connected. The reaction "Ready relay dropout" is
only activated on this NCU.
Output of alarms following EMERGENCY STOP
If an EMERGENCY STOP request is activated by the PLC on an NCU, then 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 a control panel reset. If the original
(EMERGENCY STOP) 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 acknowledged.
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 compensation functions:
● CEC
● EEC
● QEC
are not available for link axes.
Switching off grouped NCUs
If an NCU assigned to an NCU grouping is switched off or restarted by NCK RESET, then
the other NCUs in the grouping are also affected. (see also "Configuration of a link
grouping"). An alarm is generated on the NCUs which are still running to prevent them
continuing with the machining operation.
Extended Functions
Function Manual, 01/2008, 6FC5397-1BP10-3BA0
Several Operator Panels on Several NCUs, Distributed Systems (B3)
2.6 Link axes
147