![](https://profinetuniversity.com/wp-content/uploads/2016/05/S1_S2_Redundancy.png)
https://profinetuniversity.com/wp-content/uploads/2018/07/S1_S2-1024x294.png
https://profinetuniversity.com/wp-content/uploads/2018/07/R1_R2-1-1024x346.png
https://profinetuniversity.com/wp-content/uploads/2016/05/R1_R2_Redundancy-1024x346.png
https://profinetuniversity.com/wp-content/uploads/2016/05/S1_S2_Redundancy-1024x294.png
S1 and S2 system redundancy are implemented with a single NAP. S1 is actually not redundant at all, while S2 is the most simple redundant connection.