The devices you have speak Modbus RTU over a RS-485 serial two-wire network. It's a different physical wiring network than Modbus TCP over Ethernet. All should be fine daisy-chained on one RS-485 network as long as each has a unique address and wiring standards such as overall length are met.
To get that connected to the PLC, you need a RS-485 serial port that speaks RTU. I don't know Schneider well. A quick search leads me to believe that at least some models of CPU have a capable serial port on board. It might be the same style RJ-45 connector as Ethernet, but it's not Ethernet.
If serial is not on board your CPU, my first choice would probably be a Schneider serial module if you can add one to your rack. Otherwise you need a gateway to run the Modbus RTU network and interface to your controller by Modbus TCP or another protocol supported by your controller. There are several manufacturers that make suitable gateways, ProSoft, Red Lion, and Anybus are popular ones that come to mind, but there are quite a few other options.