Fgroup And Fgref - Siemens SINUMERIK 840D sl Function Manual

The identifier records in which system of units the data have been read out. This ensures that
no data sets are read into the control with a system of units other than that which is currently
set.
Since the language instruction is also evaluated in part programs, these can also be "protected"
against operator errors as described above. You can, therefore, prevent part programs
containing only metric data, for example, from running on an inch system of units.
Archive and machine data sets are downward-compatible with the following setting:
MD11220 $MN_INI_FILE_MODE = 2
Note
The INCH/METRIC operation is only generated if the compatibility machine data:
MD10260 $MN_CONVERT_SCALING_SYSTEM = TRUE
Rounding machine data
All length-related machine data is rounded to the nearest 1 pm when writing in the inch system
(MD10240 $MN_SCALING_SYSTEM_IS_METRIC=0 and MD10260
$MN_CONVERT_SCALING_SYSTEM=1), to avoid rounding problems.
This corrects the loss of accuracy resulting from conversion to ASCII when reading out a data
backup in the inch system of measurement when the data is read back into the system.
7.3.3

FGROUP and FGREF

Programming
It should be possible to program the effective machining feedrate in the usual way as a path
feedrate via the F value in processing procedures where the tool, the workpiece or both are
moved by a rotary axis (e.g. laser machining of rotating tubes).
In order to achieve this, it is necessary to specify an effective radius (reference radius) for each
of the rotary axes involved. You can do this by programming the modal NC address:
FGREF[<rotary axis>]=<reference radius>
The unit of the reference radius depends on the G70/G71/G700/G710 setting.
In order to include the axes in the calculation of the path feedrate, they must all be specified
in the FGROUP command.
In order to ensure compatibility with the behavior with no FGREF programming, the evaluation
1 degree = 1 mm is activated on system powerup and RESET.
This corresponds to a reference radius of:
FGREF = 360 mm / (2π) = 57.296 mm
This default is independent of the active basic system
(MD10240 $MN_SCALING_SYSTEM_IS_METRIC) and the currently active G70/G71/G700/
G710 setting.
Basic Functions
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
G2: Velocities, setpoint / actual value systems, closed-loop control
7.3 Metric/inch measuring system
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