Siemens SINUMERIK 840D sl Function Manual page 898

Detailed description
2.4 Frames
2.4.8.2 Zero offset external via system frames
Previous function:
The zero offset external is either defined by the PLC via the OPI or programmed in the part
program by the axis variable $AA_ETRANS[axis] = value. This zero offset is activated by the
PLC via a VDI signal.
After the PLC has activated the offset, every axis compensation value is applied with the
next block. With G64, in certain circumstances this could also be multiple blocks, if there is
no Stop at the block end.
Functional expansion:
With SW package 6 and higher, the zero offset external can be managed and enabled via a
system frame.
The system frame is configured with bit 1 in machine data
MD28082 $MC_MM_SYSTEM_FRAME_MASK = 'B0010'
.
If this bit is set, the system function will only use the system frame, disabling the existing
functionality. Values are written by the PLC (OPI) or, in the part program, with axial variables
$AA_ETRANS[axis].
As previously, activation is by the PLC, via an axial VDI signal.
If a level change of the axis signal from 0 to 1 is detected, the movement is stopped
immediately, the preprocessing is reorganized and the current system frame is written and
activated with the axis value of $AA_ETRANS[axis]. The system frame in the data
management is also described. The offset is then first applied and the interrupted motion is
continued.
With G91 and machine data setting
MD42440 $MC_FRAME_OFFSET_INCR_PROG = 0
, the zero offset external is also applied with the approach block.
Special treatment when programming incrementally is not relevant for the zero offset
external. Activation always leads to the offset being applied immediately.
The zero offset external acts on the absolute translation absolutely (coarse offset) of the
current system frame. Therefore, a multiple activation of a zero offset external does not act
additively, and only the coarse component of the translation is overwritten with the value
$AA_ETRANS[axis]. The current system frame is the system frame currently active in the
main run.
2.4.8.3 Toolholder
Translations
With kinematics of type P and M the selection of a toolholder activates an additive frame
(table offset of the orientational toolholder), which takes into account the zero point offset as
a result of the rotation of the table.
The zero offset is entered into a system frame ($P_PARTFR).
The translational part of this frame is then overwritten.
Other contents of the frame are left unchanged.
In order to be able to use this system frame, bit 2 must be set in the machine data
MD28082 $MC_MM_SYSTEM_FRAME_MASK
.
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Basic logic functions: Axes, coordinate systems, frames (K2)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0