Siemens simatic et 200s Operating Instructions Manual page 335

Example 2: Reference Point Run with Minus Limit Switch
● Start position: between the minus limit switch and the plus limit switch
● Start direction: Minus
● Reference signal: Reference switch
● Reference switch: Minus limit switch
Figure 7-12
You can also carry out synchronization at the limit switch with the following zero mark.
If the start position is on the limit switch, the 1PosU controls the drive directly in creep feed
mode in the referencing direction.
ET 200S Positioning
Operating Instructions, 05/2007, A5E00124871-04
Reference Point Run with Minus Limit Switch
1PosUniversal/Digital
7.6 Functions of the 1PosU
335