Siemens SINUMERIK 840D Function Manual page 43

MD11220 $MN_INI_FILE_MODE = 2
Note
The INCH/METRIC identifier is only generated if the compatibility machine data:
MD10260 $MN_CONVERT_SCALING_SYSTEM = TRUE
Note
Rounding machine data
All length-related machine data is rounded to the nearest 1 pm when writing in the inch system
of units (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 units when the data is read back into the system.
Input resolution and computational resolution
The input and calculation resolution is defined as an internal number of increments per
millimeter.
MD10200 $MN_INT_INCR_PER_MM
The precision of entry of linear positions is limited to the calculation resolution. The product of
the programmed position value and the calculation resolution is rounded up to the next integer.
To make the rounding clear and understandable, powers of 10 should be used for the
calculation resolution.
Example:
1 inch = 25.4 mm ⇒ 0.0001 inch = 0.00254 mm = 2.54 μm = 2540 nm
To be able to program and display the last 40 nm, a value of 100000 must be parameterized for
the input and calculation resolution.
Only with this identical setting for both systems of units is it possible to change the system of
units without a significant loss of accuracy. Once MD10200 has been set to this value, it will not
need to be changed each time the measuring system is switched over.
System of units for positioning tables
The system of units for positional data of the indexing axis tables and switching points for
software cams is configured in machine data:
MD10270 $MN_POS_TAB_SCALING_SYSTEM
Further information:
Function Manual Axis and Spindles; Software cams, position switching signals and indexing
axes
Axes and spindles
Function Manual, 06/2019, A5E47437747B AA
G2: Velocities, setpoint / actual value systems, closed-loop control
2.3 System of units, metric/inch
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