Siemens SINUMERIK 840Di Function Manual page 848

Detailed Description
2.5 Workpiece-related actual-value system
The actual values in the settable zero system (SZS) can be read from the part program for
each axis using the variable $AA_IEN[axis].
The actual values in the basic zero system (BZS) can be read from the part program for
each axis using the variable $AA_IBN[axis].
Actual-value display
The programmed contour is always displayed in the WCS.
The following offsets are added to the MCS:
• Kinematic transformation
• DRF offset/zero offset external
• Active frame
• Active tool offset of the current tool
Switchover by PLC
The actual values can be displayed in the WCS, SZS, BZS or MCS via the PLC. The PLC
can define, which coordinate system corresponds to the workpiece coordinate system on a
machine.
On MMC poweron the MCS is preset.
With the signal DB19 DBB0.7 "MCS/WCS switchover", it is also possible to switch from the
PLC to the WCS.
Transfer to PLC
Depending on machine data
MD20110 / MD20112, bit 1,
the auxiliary functions (D, T, M) are output to the PLC (or not) on selection of the tool length
compensation.
Note
If the WCS is selected from the PLC, an operator action can still be used to switch between
the WCS and MCS for the relevant mode.
However, when the mode and or area is changed, the WCS selected by the PLC is
evaluated and activated.
References:
/FB1/ Description of Functions, Basic Machine; Mode Group, Channel, Program Operation,
Reset Response (K1)
2-118
Axis Types, Coordinate Systems, Frames (K2)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0