Siemens SINUMERIK 840D sl Programming Manual page 916

Work preparation
3.16 Axis couplings
A switchover can be programmed via setting data $SA_LEAD_TYPE.
You must always switch between the actual-value and setpoint coupling when the following
axis stops. It is only possible to resynchronize after switchover when the axis is motionless.
Application example
You cannot read the actual values without error during large machine vibrations. If you use
master value coupling in press transfer, it might be necessary to switchover from actual-value
coupling to setpoint coupling in the work steps with the greatest vibrations.
Master value simulation with setpoint coupling
Via machine data, you can disconnect the interpolator for the leading axis from the servo. In this
way you can generate setpoints for setpoint coupling without actually moving the leading axis.
Master values generated from a setpoint link can be read from the following variables so that
they can be used, for example, in synchronized actions:
- $AA_LEAD_P
- $AA_LEAD_V
Create master value
As an option, master values can be generated with other self-programmed methods. The
master values generated in this way are written to and read from variables
- $AA_LEAD_SP
- $AA_LEAD_SV
Before you use these variables, the setting data $SA_LEAD_TYPE = 2 must be set.
Status of coupling
You can query the status of the coupling in the NC program with the following system variable:
$AA_COUP_ACT[[axis]]
0: No coupling active
16: Master value coupling active
Status management for synchronized actions
Switching and coupling events are managed via real-time variables:
$AC_MARKER[i] = n
managed with:
916
NCU 1
Ax1
Actual value coupling
NCU 2
Ax2
Master value position
Master value velocity
Master value position
Master value velocity
Programming Manual, 12/2019, 6FC5398-2EP40-0BA0
NC programming