Manual Switchover Of The Basic System - Siemens SINUMERIK 828D Function Manual

G2: Velocities, setpoint / actual value systems, closed-loop control
7.3 Metric/inch measuring system
NC-specific conversion factor
The default conversion factor in the machine data is:
MD10250 $MN_SCALING_VALUE_INCH (conversion factor for switchover to inch system)
set to 25.4 for converting from the metric to the inch measuring system. By changing the conversion factor, the
control system can also be adapted to customer­specific measuring systems.
Axis-specific conversion factor
The default conversion factor in the axis-specific machine data is:
MD31200 $MA_SCALING_FACTOR_G70_G71 (conversion factor when G70/G71 is active)
set to 25.4 for converting from the metric to the inch measuring system. By changing the conversion factor, the
control system can also be adapted to customer­specific measuring systems on an axis-specific basis.
7.3.2

Manual switchover of the basic system

General
The control system can operate with the metric or inch measuring system. The initial setting of the measuring
system (basic system) is defined using the following machine data:
MD10240 $MN_SCALING_SYSTEM_IS_METRIC (basic system metric).
Depending on the basic system, all length-related data is interpreted either as metric or inch measurements.
The relevant softkey on the HMI in the "Machine" operating area is used to change the measuring system of the
controller.
The change in the measuring system occurs only under the following boundary conditions:
• MD10260 $MN_CONVERT_SCALING_SYSTEM=1
• Bit 0 of MD20110 $MC_RESET_MODE_MASK is set in every channel.
• All channels are in the Reset state.
• Axes doe not traverse with JOG, DRF or PLC.
• Constant grinding wheel peripheral speed (GWPS) is not active.
Actions such as part program start or mode change are disabled for the duration of the measuring system
changeover.
If the measuring system cannot be changed, this is indicated by a message to that effect on the user interface.
These measures ensure that a consistent set of data is always used for a running program with reference to the
measuring system.
The actual change in the measuring system is made by writing all the necessary machine data and subsequently
activating them with a RESET.
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Function Manual, 09/2011, 6FC5397-0BP40-2BA0
Basic Functions