Siemens SINUMERIK 840D sl Function Manual page 384

Compensations (K3)
Interpolatory compensation
Fundamental principle
The compensation values cannot be entered directly as a 2-dimensional grid. Compensation
tables in which the compensation values are entered must be created first.
A compensation table contains the compensation values of one line (four lines in the
example, i.e. four compensation tables). The compensation values 0.1 to 0.5 are entered in
the first table in the example, the compensation values 0.6 to 1.0 in the second table, and so
on. The compensation tables are referred to below as f tables and their values as f_i(x)
(i=number of table).
The compensation values of f tables are evaluated by multiplying them by other tables. The
latter are referred to below as g tables and their values as g_i(y). The number of f tables and
g tables is equal (four in the example).
In g tables, one compensation value in each table is set to 1 and all the others to 0. The
position of compensation value 1 within the table is determined by the table number. In the
first g table, compensation value 1 is positioned at the first interpolation point and, in the
second g table, at the second interpolation point, etc. By multiplying g tables by f tables, the
correct compensation value in each f table is selected by multiplying it by 1. All irrelevant
compensation values are concealed through multiplication by 0.
Using this scheme, compensation value D
following equation:
D (x/y)=f_1(x)*g_1(y) + f_2(x)*g_2(y) + ...
z
When the compensation value for the current position of the machine spindle is calculated,
the f table values are multiplied by the g table values according to this rule.
Applied to the example, this means, for instance, that compensation value D
calculated by multiplying each of the function values f_i(500) in the f tables by the function
values g_i(300) in the g tables:
D (500/300) = f_1(1000)*g_1(300) + f_2(1000)*g_2(300) + f_3(1000)*g_3(300) +
z
f_4(1000)*g_4(300)
D (500/300) = 0.2*0 + 0.7*1 + 1.2*0 + 1.7*0 = 0.7
z
(for functions values, see also f and g tables in program code)
Program code
The application example described above can be achieved with the following part program code:
$MA_CEC_ENABLE[Z1]
NEWCONF
;Define values f_i(x) in the f tables:
384
at position (x/y) is calculated according to the
z
= FALSE ; Deactivate compensation
; by setting to FALSE.
; The table values can then be
; altered without generation of
; alarm 17070.
; Activate $MA_CEC_ENABLE
Function Manual, 03/2009, 6FC5397-1BP10-4BA0
(500/300) is
z
Extended Functions