Hello everyone, 

hope you are doing fine. 

My question is how can I make a redundant hardware redundancy between I/Os and controller when both controller and ET200SP are connected to one switch. Enclosed there is picture showing the encircled switch with red circle. How can I can I make this redundancy possible ? for example with two switch or with loop or other ways that are reliable and can not interrupt communication between ET200SP and controller. I appreciate your kind replies. 

Hi saba_149!

An explanation of the redundancy possibilities can be found at this link.