Siemens SINUMERIK 840D Function Manual page 44

G2: Velocities, setpoint / actual value systems, closed-loop control
2.3 System of units, metric/inch
User tool data
The physical units for user-defined tool and tool cutting edge data can be set in the following
machine data:
● MD10290 $MN_CC_TDA_PARAM_UNIT
● MD10292 $MN_CC_TOA_PARAM_UNIT
Note
When the system of units is switched over, all length-related tool data is converted to the new
system of units.
Channel-specific machine data
Reset position
For each channel, the reset position of G group 13 (system of units, inch/metric) is set in the
machine data:
MD20150 $MC_GCODE_RESET_VALUES[12] (reset position of G group 13)
Axis/spindle-specific machine data
Conversion factor (axis-specific)
To make pure positioning axes independent of G70/G71, a factor for converting from metric into
the inch system of units can be set in machine data:
MD31200 $MA_SCALING_FACTOR_G70_G71 (conversion factor when G70/G71 is active)
Default value: 25.4
Note
The conversion factor should be identical for all three geometry axes.
JOG and handwheel factor
The following machine data comprises two values containing axis-specific increment weighting
factors for each of the two system of units:
MD31090 $MA_JOG_INCR_WEIGHT
Depending on the actual setting in MD10240 SCALING_SYSTEM_IS_METRIC, the control
system automatically selects the appropriate value.
The user defines the two increment factors when the system is commissioned.
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Axes and spindles
Function Manual, 06/2019, A5E47437747B AA