Dimensions; Absolute Dimensions (G90, Ac) - Siemens SINUMERIK 840D sl Programming Manual

Geometry settings

8.3 Dimensions

8.3 Dimensions
The basis of most NC programs is a workpiece drawing with specific dimensions.
These dimensions can be:
• In absolute dimensions or in incremental dimensions
• In millimeters or inches
• In radius or diameter (for turning)
Specific programming commands are available for the various dimension options so that the
data from a dimension drawing can be transferred directly (without conversion) to the NC
program.
8.3.1

Absolute dimensions (G90, AC)

Function
With absolute dimensions, the position specifications always refer to the zero point of the
currently valid coordinate system, i.e. the absolute position is programmed, on which the tool
is to traverse.
Modal absolute dimensions
Modal absolute dimensions are activated with the G90 command. Generally it applies to all
axes programmed in subsequent NC blocks.
Non-modal absolute dimensions
With preset incremental dimensions (G91), the AC command can be used to set non-modal
absolute dimensions for individual axes.
Note
Non-modal absolute dimensions (AC) are also possible for spindle positioning (SPOS, SPOSA)
and interpolation parameters (I, J, K).
Syntax
G90
<axis>=AC(<value>)
Significance
G90:
AC:
<axis>:
<value>:
168
Command for the activation of modal absolute dimensions
Command for the activation of non-modal absolute dimensions
Axis identifier of the axis to be traversed
Position setpoint of the axis to be traversed in absolute dimensions
Programming Manual, 09/2011, 6FC5398-1BP40-2BA0
Fundamentals