Yaskawa YASNAC PC NC Programming Manual - Manual (Page 41)

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YASNAC PCNC Programming Manual Chapter 2: Commands Calling Axis Movements
2.2 REFERENCE POINT RETURN
2.2.1 Automatic Return to Reference Point (G28)
With the commands of “G28 X • • • Y • • • Z • • • (*a • • • b • • •);”, the numerically controlled
axes are returned to the reference point. The axes are first moved to the specified position at a
rapid traverse rate and then to the reference point automatically. This reference point return oper-
ation is possible in up to simultaneous 3-axis (* 5-axis) control. The axes not designated in the
G28 block are not returned to the reference point.
FIGURE 2.2.1.1 Automatic Reference Point Return
(1) Reference Point Return Operation
Reference point return operation is the series of operations in which the axes return to the ref-
erence point after the reference point return operation has been started manually.
Reference point return is accomplished in two ways:
(a) Low-speed reference point return
In low-speed reference point return operation, a deceleration limit switch is used. In high-
speed reference point return operation, the first return operation is executed in the low-
speed type using a deceleration limit switch; the reference point data are stored after the
completion of the first reference point return and in subsequent reference point return
operations is executed without using a deceleration limit switch.