Open Architecture in DCS

Open architecture refers to the ability in DCS to "distribute" multiple controllers throughout a process while a single PLC is limited by its I/O and proximity to the operation.

An open architecture is one that enables devices from many suppliers/manufacturers to be used directly with each other. Such devices have built-in communication interfaces than can be lugged into an industry-standard communication network like Ethernet, Foundation Fieldbus, Profibus, etc.

A closed architecture is one where devices of a given family communicate directly only with those of the same family, or those of a similar family, that are made by a single supplier/manufacturer. Making two or more mutually-incompatible closed-architecture systems or subsystems talk to each other has to be done through interfaces that translate communication between the two. For example, if an Allen-Bradley PLC were to need to 'talk' with a Modicon one, a suitable interface between the two's communication busses or in a direct, dedicated communication link would 'interpret' communication signals going both ways.

What it all boils down to is if communications are through industry-standard communication busses that aren't proprietary, the architecture's open. Otherwise, it's closed.

Cheers! DZ