Siemens SINUMERIK 840C - Manual (Page 948)

12.93 12 Functional Descriptions
12.18.14 Special cases of gearbox interpolation
• Distance-coded reference mark system for each gantry axis
To avoid the need to traverse large distances for reference point approach purposes, it is
possible to use a measuring system with distance-coded reference marks as the sole or as the
second measuring system. This measuring system is referenced after a distance of
approximately 2 cm. The referencing procedure is in this case the same as for normal
incremental measuring systems.
Note:
Please refer to functional description of "Distance-coded measuring system" for further details.
Prerequisite
• As for incremental measuring system for gantry axes
• The 1st measuring system (OB 32, DW k + 2 bit 12) must be activated in OB 20 and the
absolute offset (NC MD 1808*bit 3) of the gantry axes in FB 62.
Flowchart for PLC-controlled reference point approach
Activate control
SIPOS measuring systems send their absolute positions to the control
Activate GI grouping 1
Enable following axis overlay
Initiate on-the-fly synchronization for grouping 1
Synchronous position reached? Deactivate grouping 1
Declare absolute offset (NC MD 1808*3) for the leading and following axes to be invalid via
FB 62.
Select 2nd measuring system for leading and following axes (DB32, DWk + 2 bit 12)
Activate grouping 1
Selection reference point mode
Initiate reference point approach with leading axis X1 (following axis X follows X1)
Reference point reached?
Deactivate grouping 1
Activate grouping 2
Initiate reference point approach with leading axis X (following axis X1 follows X)
Reference point reached?
Enable following axis overlay
Initiate on-the-fly synchronization for grouping 2
Synchronization reached? (following axis)
Disable following axis overlay
Select "Automatic" mode
END
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SINUMERIK 840C (IA)