Siemens SINUMERIK 840D sl Programming Manual page 144

Feed control
7.8 Feedrate with handwheel override (FD, FDA)
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
N20 POS[V]=100 FAD[V]=200
Traversing range:
The traversing range is limited by the starting position and the programmed end point.
144
Description
; Axial feedrate = 100 mm/min
; Axial target position = 100, axial feedrate = 200 mm/min
; and velocity override with handwheel.
; Acceleration from 100 to 200 mm/min in N20. The
; handwheel can be used to vary the velocity dependent on the
; direction of rotation
; between 0 and the maximum value (machine data).
Programming Manual, 09/2011, 6FC5398-1BP40-2BA0
Fundamentals