Methods and apparatus to implement communications via a remote terminal unit are disclosed. An example apparatus includes a first central processing unit module to be in communication with a host of a process control system. The example apparatus also includes a first rack including a backplane and a plurality of slots. The plurality of slots includes a master slot to receive the first central processing unit module. The backplane communicatively couples the first central processing unit module to at least one of a first communication module or a first input/output (I/O) module inserted in a second one of the slots. The backplane includes a first communication bus for communication of I/O data and a second communication bus for communication of at least one of maintenance data, pass-through data, product information data, archival data, diagnostic data, or setup data. The first communication bus is independent of the second communication bus.