Siemens SINUMERIK 840D sl Function Manual page 1634

Detailed Description
2.1 Spindle modes
Positioning from standstill
A distinction is made between two cases with regard to positioning from standstill:
• Case 1: The spindle is not synchronized.
• Case 2: The spindle is synchronized.
Figure 2-3
24
This is the case if the spindle is to be positioned after switching on the control and drive
or after a gear step change (e.g., for a tool change).
MD31040 $MA_ENC_IS_DIRECT = 0
This is the case if, after switching on the control and drive, the spindle is to be rotated
through a minimum of one revolution with M3 or M4 and then stopped with M5
(synchronization with the zero mark) before the first positioning action.
Positioning with stationary spindle
Basic logic functions: Spindles (S1)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0