Siemens simatic et 200s Operating Instructions Manual page 137

When the assigned parameter conditions are met, the axis is synchronized. The
1PosInc/Analog sets the feedback signal SYNC = 1, assigns the reference point coordinates
to the actual value, and decelerates to 0 V.
Figure 4-12
Control Signals: Search for Reference
Address
Byte 0
Bytes 1 to 3
ET 200S Positioning
Operating Instructions, 05/2007, A5E00124871-04
Sequence of Execution of the Search for Reference
Assignment
Bits 0.7 to 0.4:
Bit 7 6
0 0
Bit 2: DIR_M
Bit 1: DIR_P
Bit 0: START
Reference point coordinates
(linear axis: 0 to 16 777 215; rotary axis: 0 to end of rotary axis - 1)
4.6 Functions of the 1PosInc/Analog
5 4
MODE 3 = Reference Point Run
1 1
1PosInc/Analog
137