Siemens SINUMERIK 840D sl Programming Manual page 130

Fundamentals
2.7 Feed control
Traverse positioning axes with path default (FDA[<axis>]=0)
In the NC block with programmed FDA[<axis>]=0 the feed is set to zero so that the program
cannot generate any travel movement. The programmed travel movement to the target position
is now controlled exclusively by the operator rotating the handwheel.
Example:
Program code
...
N20 POS[V]=90 FDA[V]=0
Direction of movement, travel velocity
The axes follow the path set by the handwheel in the direction of the sign. Forward and
backwards travel is possible dependent on the direction of rotation. The faster the handwheel
rotates, the higher the traversing speed.
Traversing range:
The traversing range is limited by the starting position and the programmed end point.
Traverse positioning axis with velocity override (FDA[<axis>]=<velocity>)
In NC blocks with programmed FDA[...]=..., the feedrate from the last programmed FA value is
accelerated or decelerated to the value programmed under FDA. Starting from the current
feedrate FDA, the handwheel can be turned to accelerate the programmed movement to the
target position or decelerate it to zero. The values set as parameters in the machine data serve
as the maximum velocity.
Example:
Program code
N10 POS[V]=... FA[V]=100
130
Description
; Target position = 90 mm, axial feedrate = 0 mm/min and
path override with handwheel.
; Velocity of axis V at start of block = 0 mm/min.
; Path and speed defaults are set using handwheel pulses
Description
; Axial feedrate = 100 mm/min
Programming Manual, 12/2019, 6FC5398-2EP40-0BA0
NC programming