Siemens sinumerik 840d Programming Manual page 312

Path Traversing Behavior
9
9.3 Curve tables, CTABDEF, CTABEND, CTAB, CTABINV
840D 840D
NCU 571 NCU 572
NCU 573
Function
You can use curve tables to program position and
velocity relationships between 2 axes.
Example: Replace mechanical cam plates.
The curve table forms the basis for the axial leading
value coupling by creating the functional relationship
between the leading and the following value:
The control calculates a polynomial that corresponds
to the cam plate from the relative positions of the
leading and following axes.
Additional notes
To create curve tables the memory space must be
reserved by setting the machine data.
Definition of a curve table
CTABDEF, CTABEND
A curve table represents a part program or a section
of a part program which is enclosed by CTABDEF at
the beginning and CTABEND at the end.
Within this part program section, unique following
axis positions are assigned to individual positions of
the leading axis by traverse statements and used as
intermediate positions in calculating the curve
definition in the form of a polynomial up the 3rd
order.
The starting value for the beginning of the definition
range of the curve table are the first associated axis
positions specified (the first traverse statement)
within the curve table definition. The end value of the
definition range of the curve table is determined in
accordance with the last traverse command.
Within the definition of the curve table, you have use
of the entire NC language.
9-312
810D 840Di
SINUMERIK 840D/840Di/810D/FM-NC Programming Guide Advanced (PGA) – 04.00 Edition
Y
X
Following value
= Intermediate positions
Curve definition
Definition range
Starting value
 Siemens AG 2000. All rights reserved
08.97
9
x y
5 a +a +a x 2 ...
0 1 2
7 a +a x...
0 1
12 ......
Leading
value
End value