Siemens SINUMERIK 840C - Manual (Page 695)

12.93 10 Axis and Spindle Installation
10.2.2 Input, display and position control resolution
Display resolution
In addition to the input resolution, the user must also define the display resolution. In contrast
to the input resolution, the display resolution is defined separately for each axis. NC MD 1800*,
bits 4-7, are provided for this purpose. The display resolution defines the number of decimal
places that are to be displayed. The default value for all axes is 10
-3 mm or degrees.
The display resolution must have the same input system (inch - metric - degrees) as the input
resolution. Alarm 4 (Power on Alarm) is issued to flag "Illegal input system" if this is not the
case.
A display resolution < 10 -3 degrees is only possible for rotary axes if the option is available.
Position control resolution (Measuring System - MS)
Like the display resolution, the position control resolution is defined on an axis-specific basis.
This must be taken into account when entering machine data stored in the measuring system.
MD 1800*, bits 0-3, are used to define the position control resolution.
The unit system must be the same for each position control resolution.
The unit system (inch - metric - degrees) used for the position control resolution need not
necessarily be identical to the one used for the input resolution.
Note:
A position control resolution < 10 -3 degrees is only possible for rotary axes if the option is
available.
Position control, input and measuring system resolutions
On the SINUMERIK 840C, position control resolution and input resolution can be entered
separately. In order to obtain a closed position control loop, the pulses arriving from the digital
measuring system and the control accuracy must be matched.
The units ”unit (MS)” for the position control resolution and ”unit (IS)” for input resolution are
used as new units of measurement.
The following applies:
1 unit (MS) = 2 units of position control resolution
1 unit (IS) = 1 unit of input resolution
Example:
Assuming a position control resolution of 0.0005 mm and an input resolution of 0.001 mm the
following applies:
1 unit (IS) = 1 unit (MS) = 1 µ m
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SINUMERIK 840C (IA)