Siemens SINUMERIK 840D sl Function Manual page 341

Special features of incremental travel
If, during incremental travel, the fixed point is reached before the increment is completed,
then the increment is considered to have been completed fully. This is the case even when
only whole increments are traveled.
MD11346 $MN_HANDWH_TRUE_DISTANCE = 2 or 3
Features of modulo rotary axes
Modulo rotary axes can approach the fixed point in both directions. The shortest path (DC) is
not observed during the travel.
Features of spindles
A spindle changes to the positioning mode on actuating the "Approaching fixed point in JOG"
function. The closed loop position control is active and the axis can traverse to the fixed
point.
If no zero mark is detected the alarm message in the axis operation is output:
Alarm 17810 "Channel %1 Axis %2 not referenced"
As a spindle must also be a modulo rotary axis at all times, the same conditions apply for
direction observation as for modulo rotary axes (refer to the paragraph "Features of modulo
rotary axes")
Extended Functions
Function Manual, 03/2009, 6FC5397-1BP10-4BA0
Manual and Handwheel Travel (H1)
Approaching a fixed point in JOG
341