Siemens SINUMERIK 840Di Function Manual page 393

Default settings:
Metric system
1000 (0.001 mm)
Example:
1 inch = 25.4 mm ⇒ 0.0001 inch = 0.00254 mm = 2.54 μm
To be able to program and display the last 40 mm, MD10200 must be assigned a value of
100000.
Only with this identical setting for both measuring systems is it possible to change the
measuring system 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.
JOG and handwheel factor
Machine data:
MD31090 $MA_JOG_INCR_WEIGHT
consists of two values, which contain the axial increment factors for both measuring
systems.
Depending on the current setting in machine data:
MD10240 $MN_SCALING_SYSTEM_IS_METRIC,
the control selects the correct value automatically.
The user defines the two increment factors, e.g. for the first axis, during the installation and
startup phase:
• Metric:
• Inch:
In this way, MD31090 does not have to be written on every inch/metric switchover.
Remaining distances are not accumulated during incremental traversing with JOG when the
measuring system is changed, since all internal positions always refer to mm.
Data backup
Data sets, which can be read separately from the control and have access to data relevant to
the measuring system, receive an INCH or METRIC identifier during the read action,
depending on machine data:
MD10260 $MN_CONVERT_SCALING_SYSTEM.
The identifier corresponds to machine data:
MD10240 $MN_SCALING_SYSTEM_IS_METRIC.
This records the measuring system, in which the data were originally read out.
Velocities, Setpoint/Actual-Value Systems, Closed-Loop Control (G2)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
MD31090 $MA_JOG_INCR_WEIGHT[0;AX1]=0.001 mm
MD31090 $MA_JOG_INCR_WEIGHT[1;AX1]=0.00254 mm ≙ 0.0001 inch
2.2 Metric/inch measuring system
Inch system
0.0001
Detailed Description
2-19