Siemens SINUMERIK 840D Function Manual page 704

H1: Manual traversing
17.13 Use of handwheels in automatic mode
Path definition
With axis feedrate = 0 (e.g. FDA[AXi] = 0), the traversing movement of the positioning axis
towards the programmed target position is controlled entirely by the user rotating the assigned
handwheel.
The direction in which the handwheel is turned determines the traversing direction of the axis.
The programmed target position cannot be exceeded during handwheel override. The axis can
also be moved toward the programmed target position from the opposite direction, whereby the
movement is only restricted by the axial position limitations.
A block change occurs when:
● The axis has reached the programmed target position
or
● The distance-to-go is deleted by axial interface signal
DB31, ... DBX2.2 (delete distance-to-go).
From this moment on, the path default is deactivated and any further handwheel pulses have
no effect.
After this, incrementally programmed positions refer to the point of interruption and not to the
last programmed position.
Velocity override
With regard to the velocity override, a distinction is made between axis feedrate and path
feedrate.
● Axis-velocity override (FDA[AXi] > 0):
The positioning axis is moved to the target position at the programmed axial feedrate. Using
the assigned handwheel, it is possible to increase the axis velocity or to reduce it to a
minimum of zero depending on the direction of rotation. The resulting axis feedrate is limited
by the maximum velocity. However, the axis cannot be traversed in the opposite direction
to that programmed.
The block change is performed as soon as the axis reaches the programmed target position.
This causes the velocity override to be deactivated automatically and any further handwheel
pulses have no effect.
Similarly, this also applies to concurrent positioning axes, where the target position and the
velocity are defined by the PLC.
● Path-velocity override (FD > 0):
The path axes programmed in the NC block traverse to the target position at the
programmed feedrate. If the velocity override is active, the programmed path velocity is
overridden by the velocity generated with the handwheel of the 1st geometry axis. The block
change is performed as soon as the programmed target position is reached.
The path velocity is increased or reduced to a minimum of zero depending on the direction
of rotation of the handwheel. However, it is not possible to reverse the direction of
movement with handwheel override.
704
Axes and spindles
Function Manual, 06/2019, A5E47437747B AA