1 passing over the reference marks, Axes (see also section "reference marks") – HEIDENHAIN TNC 407 (243 020) Technical Manual User Manual
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2.1 Passing over the reference marks
The reference marks for axes must be passed after switching on the control. This can be achieved
by
•
pressing the external START key. The axis sequence is determined by machine parameter
MP1340.X (automatic passing of the reference marks),
•
pressing the external axis direction keys. The sequence is determined by the operator.
Only after passing over the reference mark
•
can the software limits be activated,
•
can the most recently set datum point be reproduced,
•
is PLC positioning and positioning with the miscellaneous functions M91 and M92 possible,
•
is the counter value set to zero for non-controlled axes.
For distance-coded measuring systems the machine datum (MP960.x) is reference to the Zero-
Reference mark. In linear measurement systems the Zero-Reference mark is the first reference
mark after the start of the measuring length; in angular measurement systems the Zero-Reference
mark is marked.
The direction of traverse and the velocity on passing the reference marks is defined by machine
parameters (MP1320, MP1330.X).
The functional sequence for passing the reference marks can be fixed specifically for the axes by
machine parameters (MP1350.X).
The operating condition "PASS OVER REFERENCE MARKS" is sent to the PLC by the NC (W272). If
the operating mode is changed before all reference marks have been passed, the Soft key "PASS
OVER REFERENCE" will appear. The markers M2136 to M2140 inform the PLC for which axes the
reference marks have not yet been crossed.
In order to avoid exceeding the traverse range when passing over the reference marks a trip dog
(reference end-position) is necessary. This trip dog must be fixed at the end of the traverse range by
the manufacturer of the machine. The trigger signal from the trip dog is connected to an available
PLC input. In the PLC program this PLC input is combined with the markers for "Reference end-
position" (M2506, M2556 to M2559).