Points To Note - Siemens SINUMERIK 808D Function Manual

7.3.3

Points to note

Channelspecific referencing
Gantry axes can also be referenced on a channel-specific basis:
DB3200. DBX0001.0 (activate referencing)
The value of the leading axis machine data is used for the axis sequence during channel-specific referencing:
MD34110 REFP_CYCLE_NR (axis sequence for channel-specific referencing)
After the reference point of the leading axis has been reached, the synchronized axis is referenced first as described above.
Referencing from part program with G74
The referencing and synchronization process for gantry axes can also be initiated from the part program by means of
command G74. In this case, only the axis name of the leading axis may be programmed. The operational sequence is
analogous to that described for axis-specific referencing.
Position measuring system with distancecoded reference marks
In order to ensure that large distances do not need to be traversed while approaching the reference point, it is possible to
use a position measuring system with distance-coded reference markers as the only measuring system for gantry axes. In
this way the measuring system is referenced after traversal of a short path (e.g. 20 mm). The procedure for referencing the
gantry axes is the same as that described for the normal incremental measuring system.
Absolute encoder
During the synchronization compensatory motion, all the axes in the gantry axis grouping (in the decoupled state) also
traverse to the reference point value of the leading axis, which is defined in the following machine data:
MD34100 REFP_SET_POS (reference point value/destination point for distance-coded system)
The absolute encoders and distance-coded encoders of the leading axis will be set to the current actual position of the
leading axis or to the reference point value; either of these options is set using the following machine data:
MD34330 REFP_STOP_AT_ABS_MARKER
(distance-coded linear measuring system without destination point)
Activation of axis compensations
Compensation functions can be activated for both the leading axis and the synchronized axis. Compensation values are
applied separately for each individual gantry axis. These values must therefore be defined and entered for the leading axis
and the synchronized axes during start-up.
The compensations do not become operative internally in the control until the axis is referenced or the gantry grouping is
synchronized. The following applies:
Compensation type
Backlash compensation
LEC
Sag compensation
If active compensation causes the synchronized axis to move, a traverse command is displayed for the synchronized axis,
independently of the leading axis.
Monitoring functions effective
Analogous to normal NC axes, the following monitoring functions do not take effect for gantry axes until the reference point
is reached (IS "Referenced/Synchronized"):
● Working area limits
● Software limit switch
● Protection zones
The axial machine data values are used as monitoring limit values for the synchronized axis as well.
Function Manual
01/2017
Takes effect when
Axis is referenced
Axis is referenced
Gantry grouping is synchronized
PLC interface signal
"Referenced/Synchronized"
"Referenced/synchronized"
"Gantry grouping is synchronized"
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