Reference Point Return; Automatic Return To Reference Point (G28) - Siemens Sinumerik 802D sl Programming Manual

04.07
2.3

Reference point return

2.3.1

Automatic return to reference point (G28)

Format
G28 X... Z... ;
With the commands of "G28 X(U)... Z(W)... (C(H)... Y(V)...);", the numerically con-
trolled 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 automati-
cally. The axes not designated in the G28 block are not returned to the reference
point.
In case incemental encoders are used, manual reference point return needs to be
carried out before using G28.
Reference position
The reference position is a fixed position on a machine tool to which the tool can
easily be moved by the reference position return function. For example, the refer-
ence position is used as a position at which tools are automatically changed. Up to
four reference positions can be specified by setting coordinates in the machine
coordinate system in MD 34000, REFF_SET_POS.
Example of programming
(G90/G91) G28 X(U) ⋅⋅⋅ Z(W) ⋅⋅⋅ (C(H) ⋅⋅⋅);
Fig. 2-24
© SIEMENS AG 2007 All rights reserved
SINUMERIK 802D sl/840D sl840D/840Di sl/840Di/810D ISO Turning -- 04.07 Edition
Intermediate positioning point
+X
Positioning
Start
point
W
Z
Reference point return
Commands Calling Axis Movements
2.3 Reference point return
Z-axis deceleration LS
Reference point
(A fixed point in the machine)
U
2
X
Reference point return operation
2
+Z
2-47