Siemens SINUMERIK 840D sl Function Manual page 227

Applications
The DRF offset can be used, for example, in the following application cases:
● Offsetting tool wear within an NC block
Where NC blocks have very long processing times, it becomes necessary to offset tool
wear manually within the NC block (e.g. large surface-milling machines).
● Highly precise offset during grinding
● Simple temperature compensation
Note
The zero offset introduced via the DRF offset is always effective in all modes and after a
RESET. It can, however, be suppressed non-modally in the part program.
Velocity reduction
The velocity generated using the handwheel for DRF can be reduced with respect to the JOG
velocity:
MD32090 $MA_HANDWH_VELO_OVERLAY_FACTOR (ratio of JOG velocity to handwheel
velocity (DRF))
DRF active
DRF must be active to allow the DRF offset to be modified by means of traversal with the
handwheel. The following requirements must be fulfilled:
● AUTOMATIC mode
● DB21, ... DBX0.3 (activate DRF) = 1
The DRF offset can be activated/deactivated for specific channels using the "program control"
function on the HMI user interface.
The HMI software then sets interface signal:
DB21, ... DBX24.3 (DRF selected) =1.
The PLC program (basic PLC program or user program) transfers this interface signal to
interface signal
DB21, ... DBX0.3 (activate DRF) once the corresponding logic operation has been performed.
Control of DRF offset
The DRF offset can be modified, deleted or read:
User:
Part program:
Extended Functions
Function Manual, 10/2015, 6FC5397-1BP40-5BA3
4.13 Use of handwheels in automatic mode
● Traversing with the handwheel
● Reading via axis-specific system variable $AC_DRF[<axis>]
● Deleting via parts-program command (DRFOF) for all axes in a
channel
● Non-modal suppression via parts-program command (SUPA)
References:
Programming Manual, Fundamentals
H1: Manual and handwheel travel
227