Siemens SINUMERIK 840D sl Function Manual page 416

Detailed description
2.2 Metric /inch measuring system
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.
This information is intended to prevent data sets from being read into the control system with
a measuring system, which is different from the active system. In this case, alarm 15030 is
triggered and the write process is interrupted.
Since the language instruction is also evaluated in parts programs, these can also be
"protected" against operator errors as described above. You can, therefore, prevent parts
programs containing only metric data, for example, from running on an inch measuring
system.
Archives and machine data sets are downward compatible if:
MD11220 $MN_INI_FILE_MODE = 2.
Note
The INCH/METRIC instruction is only generated if compatibility machine data:
MD10260 $MN_CONVERT_SCALING_SYSTEM
is set.
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MD31090 $MA_JOG_INCR_WEIGHT[0;AX1]=0.001 mm
MD31090 $MA_JOG_INCR_WEIGHT[1;AX1]=0.00254 mm ≙ 0.0001 inch
Basic logic functions: Velocities, Setpoint/Actual Value Systems, Closed-Loop Control (G2)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0