Siemens SINUMERIK 840D Function Manual page 194

P2: Positioning axes
6.3 Motion behavior and interpolation functions
Alternatives
Initial state: The axis is controlled by the PLC. As a result of a channel stop, the channel is in
the "interrupted" state.
● Axis state "inactive" ⇒
– The stop state is canceled.
– If the axis is started, this directly results in axis motion.
● Axis state "active" ⇒
– The stop state is not canceled.
– Generate the axis state according to Use case 2 "Stop axis".
– Resume axis motion according to Use case 3 "Continue axis motion".
● A reset is performed in the channel ⇒
This process is asynchronous to control acceptance by the PLC. The two previously
mentioned alternatives can occur or the axis is assigned to the channel and is reset.
Boundary conditions
Axes/spindles, traversed by an NC program, cannot be transferred to the PLC. Axes/spindles,
which are traversed by static synchronized actions or as oscillating axis, as neutral axis,
concurrent positioning axis or command axis, can be transferred.
Relinquish axis control by the PLC
Description of the sequence:
1. PLC → NC: The PLC returns axis control to the NC
DB31, ... DBX28.7 = 0 (PLC controls axis)
2. NC: Checks whether an axial alarm is present.
3. NC: Checks whether a movement has been activated that has still not been completed? If
yes, then the movement is stopped with an axial stop according to Use case 2 "Stop axis/
spindle".
4. NC: Carries out an axial reset corresponding to Use case 4 "Reset axis/spindle".
5. NC confirms the acceptance:
DB31, ... DBX63.0 = 0 (reset executed)
DB31, ... DBX63.1 = 0 (PLC controls the axis)
DB31, ... DBX63.2 = 0 (axis stop active)
System variable $AA_SNGLAX_STAT = 0
Result: The NC has now taken over control of the axis/spindle.
Alternatives
In the following cases the NC confirms the transfer - but internally sets the "stopped" channel
state for the axis/spindle:
● The channel is in the "interrupted" state
● A stop alarm is active for the channel
● A stop alarm is active for the mode group
194
Axes and spindles
Function Manual, 06/2019, A5E47437747B AA