Fundamentals
Incremental dimensions (G91, IC)
Incremental dimensions (G91, IC)
Function
With incremental dimensions, the position specification refers to the last point approached, i.e.
the programming in incremental dimensions describes by how much the tool is to be traversed.
Modal incremental dimensions
Modal incremental dimensions are activated with the G91 command. Generally it applies to all
axes programmed in subsequent NC blocks.
Non-modal incremental dimensions
With preset absolute dimensions (G90), the IC command can be used to set non-modal
incremental dimensions for individual axes.
Note
Non-modal incremental dimensions (IC) are also possible for spindle positioning (SPOS,
SPOSA) and interpolation parameters (I, J, K).
Syntax
G91
<axis>=IC(<value>)
Significance
G91:
Command for the activation of modal incremental dimensions
IC:
Command for the activation of non-modal incremental dimensions
<axis>:
Axis identifier of the axis to be traversed
<value>:
Position setpoint of the axis to be traversed in incremental dimensions
G91 extension
For certain applications, such as scratching, it is necessary that only the programmed distance
is traversed in incremental dimensions. The active zero offset or tool length compensation is
not traversed.
This behavior can be set separately for the active zero offset and tool length compensation via
the following setting data:
This document constitutes a free excerpt compiled by the user himself/herself from the documentation provided by Siemens for this product. Siemens disclaims
all liability for the completeness of this document. It shall only be used for the user's own internal purposes. It shall not be passed on to third parties. The complete
documentation can be found at:
/dokumentation/default.aspx?DocVersionId=19801054987&Language=en-US&TopicId=14235329163
6/19/2017
Fundamentals
Incremental dimensions (G91, IC)
SD42440 $SC_FRAME_OFFSET_INCR_PROG (zero offsets in frames)
SD42442 $SC_TOOL_OFFSET_INCR_PROG (tool length compensations)
Value
Meaning
0
With incremental programming (incremental dimensions) of an axis, the zero offset or the tool
length compensation is not traversed.
1
With incremental programming (incremental dimensions) of an axis, the zero offset or the tool
length compensation is traversed.
Examples
Example 1: Milling
Program code
Comment
N10 G90 G0 X45 Y60 Z2 T1 S2000 M3
; Absolute dimension input, in rapid traverse to
position XYZ, tool selection, spindle on with
clockwise direction of rotation
N20 G1 Z-5 F500
; Linear interpolation, feed of the tool.
N30 G2 X20 Y35 I0 J-25
; Clockwise circular interpolation, circle end point
in absolute dimensions, circle center point in
incremental dimensions.
N40 G0 Z2
; Traverse
N50 M30
; End of block
This document constitutes a free excerpt compiled by the user himself/herself from the documentation provided by Siemens for this product. Siemens disclaims
all liability for the completeness of this document. It shall only be used for the user's own internal purposes. It shall not be passed on to third parties. The complete
documentation can be found at:
/dokumentation/default.aspx?DocVersionId=19801054987&Language=en-US&TopicId=14235329163
6/19/2017
Fundamentals
Incremental dimensions (G91, IC)
Note
For information on the input of the circle center point coordinates I and J, see Section "Circular
interpolation".
Example 2: Turning
Program code
Comment
N5 T1 D1 S2000 M3
; Loading of tool T1, spindle on with clockwise direction of
rotation.
N10 G0 G90 X11 Z1
; Absolute dimension input, in rapid traverse to position XZ.
N20 G1 Z-15 F0.2
; Linear interpolation, feed of the tool.
N30 G3 X11 Z-27 I-8 K-6
; Counterclockwise circular interpolation, circle end point in
absolute dimensions, circle center point in incremental
dimensions.
N40 G1 Z-40
; Traverse
N50 M30
; End of block
Note
For information on the input of the circle center point coordinates I and J, see Section "Circular
interpolation".
Example 3: Incremental dimensions without traversing of the active zero offset
Settings:
•
•
G54 contains an offset in X of 25
SD42440 $SC_FRAME_OFFSET_INCR_PROG = 0
This document constitutes a free excerpt compiled by the user himself/herself from the documentation provided by Siemens for this product. Siemens disclaims
all liability for the completeness of this document. It shall only be used for the user's own internal purposes. It shall not be passed on to third parties. The complete
documentation can be found at:
/dokumentation/default.aspx?DocVersionId=19801054987&Language=en-US&TopicId=14235329163
6/19/2017
Fundamentals
Incremental dimensions (G91, IC)
Program code
Comment
N10 G90 G0 G54 X100
See also
N20 G1 G91 X10
; Incremental dimensions active, traversing in X of 10 mm (the zero offset
is not traversed).
N30 G90 X50
; Absolute dimensions active, traverse to position X75 (the zero offset is
traversed).
→ Absolute and incremental dimensions for turning and milling (G90/G91)
This document constitutes a free excerpt compiled by the user himself/herself from the documentation provided by Siemens for this product. Siemens disclaims
all liability for the completeness of this document. It shall only be used for the user's own internal purposes. It shall not be passed on to third parties. The complete
documentation can be found at:
/dokumentation/default.aspx?DocVersionId=19801054987&Language=en-US&TopicId=14235329163
6/19/2017