On recent release of Redundancy SL for soft PLC, i am planning to involve in my Control System. So i am building a POC for it.

I have gone through this that it supports

The following fieldbuses are supported:
EtherCAT (3S-Smart Software Solutions GmbH Stack)
Profibus via Hilscher CIF50 card

Does it means the redundant controller should be connected to master controller only through EtherCAT or Profibus.

What is it about?

I think it means your Remote I/O and fieldbus devices can only be switched over to the redundant controller if they are EtherCAT or Profibus based.

Take a look at the red line on this graphic from the store page

So you see that in addition to the EtherCAT link, there is also a dedicated network link between the two PLCs (the red line). There is also a third network to link to the rest of the plant.

Hi Ian

It means the redundant connection can be based on any kind of TCP/UDP based protocols.

But what is this compatible statement of fieldbuses are supported:
EtherCAT (3S-Smart Software Solutions GmbH Stack)
Profibus via Hilscher CIF50 card.

I am not getting this?

Well, a redundant-controller fieldbus is not as simple as a single-controller fieldbus.
Modbus TCP, for example, you have some devices which only allow one client connection at a time. . . If you lose the Primary, the Secondary must wait for the conneciton to time out at the modbus device.
So currently, only EtherCAT and Profibus via Hilscher CIF50 have been implemented and tested for this.