Siemens SINUMERIK 840Di sl Function Manual page 54

Detailed description
2.4 Actions in synchronized actions
Lower limit = 0
The polynomial (no. 2) can therefore be defined as follows:
FCTDEF(2, 0, 120, 160, -2, 0, 0)
This function completely describes the Figure "Example of multiplicative control".
The associated synchronized action can be programmed as follows:
ID = 1 DO SYNFCT(2, $AC_OVR,
$AA_LOAD[x])
Position offset with limitation
The system variable $AA_OFF controls an axis-specific override that takes immediate effect
(basic coordinate system). The type of override is defined by the machine data:
MD36750 $MA_AA_OFF_MODE (Effect of value assignment for axial override in case of
synchronized actions)
0: Proportional evaluation
1: integral evaluation
In SW 4 and later, it is possible to limit the value to be compensated absolutely (main-run
variable output) to the value stored in the setting data:
SD43350 $SA_AA_OFF_LIMIT (Upper limit of the offset value $AA_OFF in case of
clearance control)
Axis-specific system variables can be evaluated in another synchronized action to establish
whether the limitation has been reached.
$AA_OFF_LIMIT[axis]
Value -1: Limit of offset value reached in the negative direction.
Value 1: Limit of offset value reached in the positive direction.
Value 0: The offset value is not within the limit range.
Application:
The SYNFCT function can be used in conjunction with system variable $AA_OFF to
implement clearance control in laser machining operations. See below.
Example
Task:
Clearance control as function of a sensor signal in case of laser machining.
The offset value is limited in the negative Z direction to ensure that the laser head is
retracted reliably from finished metal blanks. When the limiting value is reached, the user
can trigger the reactions such as Stop axis (by means of override 0, see Chapter "Disabling
a programmed axis motion") or set alarm (see Chapter "Set alarms / error reactions").
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; the path override is calculated in each interpolation cycle
from the percentage drive load for the x axis via the
polynomial 2
Function Manual, 11/2006, 6FC5397-5BP10-2BA0
Synchronized actions