Siemens SINUMERIK 840DE

Positional Data
3.9 Reference point approach (G74)
Fundamentals
3-32 Programming Manual, 10.2004 Edition, 6FC5 298-7AB00-0BP1
3.9 Reference point approach (G74)
Function
When the machine has been powered up (where incremental position measurement systems
are used), all of the axis slides must approach their reference point. Only then can traversing
movements be programmed.
The reference point can be approached in the NC program with G74.
Programming
G74 X1=0 Y1=0 Z1=0 A1=0 ... programmed in a separate NC block
Parameters
G74 Homing
X1=0 Y1=0 Y1=0…
A1=0 B1=0 C1=0…
The stated machine address
X1, Y1, Z1… for linear axes is approached in the reference
point
A1, B1, C1… for rotary axes is approached in the reference
point
Note
A transformation should not be programmed for an axis which is to approach the reference
point with G74.
The transformation is deactivated with commandTRAFOOF.
Example
When the measurement system is changed, the reference point is approached and the
workpiece zero is initialized.
N10 SPOS=0 Spindle in position control
N20 G74 X1=0 Y1=0 Z1=0 C1=0 Reference point approach for linear axes
and rotary axes
N30 G54 ;Zero offset
N40 L47 Cutting program
N50 M30 ; End of program