Siemens SINUMERIK 840C Installation Instructions Manual page 832

10.94
Parking axis
If a C axis is assigned to a spindle via MD 461*, axis-specific interface signals (DB 32) are also
evaluated. Two axis-specific signals in particular should be mentioned here that have feedback
effects on spindle operation.
The measuring circuit monitoring functions are switched off by setting the signal PARKING
AXIS. Then, no alarm appears if the connection between encoder and measuring circuit
module is broken (for instance, in order to detach the axis from the machine).
The signals SPINDLE SYNCHRONIZED and REFERENCE POINT REACHED are reset, the
speed controller enabling command cancelled and the C axis automatically switched to follow-
up mode.
The actual values are not activated.
The encoder frequency monitoring and measuring circuit monitoring functions of the C-axis
encoder are automatically deactivated in spindle operation.
Note:
• The interface signal PARKING AXIS must never be cancelled in synchronous operation
because the request for re-synchronization of the spindle is linked to this signal. This
would, however, cause disturbances in synchronized operation.
Re-synchronization of the spindle in synchronous operation is generally not permitted.
• If positioning mode is requested by the NC or PLC before the signal SPINDLE
SYNCHRONIZED has been set again, then the spindle traverses the zero mark again
before it approaches the programmed position.
• If the signal SPINDLE SYNCHRONIZED is cancelled in C-axis mode, then the axis must
be referenced explicitly again (e.g. with G74) immediately afterwards.
Setting the signals in the C axis mode produces the following results:
• PARKING AXIS 0 1
– The measuring circuit monitoring functions are deactivated.
– The actual value display of the spindle position is no longer refreshed in the basic
screen.
– The axis-specific signal REFERENCE POINT REACHED is cancelled.
– The spindle-specific signal SPINDLE SYNCHRONIZED is cancelled.
– Position control is interrupted.
– The analog speed setpoint 0 is output.
– The speed controller enabling is cancelled.
When the signals are reset, the results are as follows:
• PARKING AXIS 1 0
Re-synchronizing of the spindle is necessary because the C axis too is always related to the
zero mark of the spindle. The two possible ways of synchronizing are:
• Overtravelling the zero mark with any spindle motion
• Explicit reference point approach in the C axis mode (manually or with program via G74)
Note:
• If the positioning mode is requested by the NC or PLC system before the SPINDLE
SYNCHRONIZED signal is set again, the spindle will first pass the zero mark before it
approaches the programmed position.
© Siemens AG 1992 All Rights Reserved
SINUMERIK 840C (IA)
6FC5197- AA50
12 Functional Descriptions
12.7.2 Description of the spindle modes
12–57