Siemens SIMATIC S5 Manual page 160

Machine Data, Modes and Traversing Programs
• G74: Approach to reference point
This function can be used to approach an existing physical reference point.
The position specified by the value of the reference coordinate is not
approached; this position may differ from that of the physical reference point
due to compensations or offsets.
The incremental speed specified in the machine data is used as approach
speed.
Note:
The G74 function does not execute a reference point approach on the same
basis as mode 5.
The zero offsets and tool offsets currently in force are taken into account in
the actual-value display.
Example:
Following an approach to reference point and subsequent positioning, the
drive is at the position - 50.
Following a zero offset, the actual position is 50 mm and the reference point
position is 100 mm.
Function G74 moves the drive to the position 100 mm, which is the physical
zero point (not to coordinate 0, which is the reference coordinate specified in
the machine data).
ZO = 50 mm
0
G74
0
5-88
Position of the drive
-50 0
Reference coordinate set via mode 5
50 100
50 100
IP 266
EWA 4NEB 812 6057-02