| First let me paraphrase the question: Is it possible to fabricate an actuator for different networks or is it necessary to buy the actuator for networks supported by its manufacturer? This is actually a good question that allows me to advocate standardized networks for industrial automation. There are two parts to this question, depending on the discussion of process control networks or discrete manufacturing networks. For process control, the international standard for fieldbus networks is defined by IEC 61158 that includes Foundation Fieldbus, Profibus, ControlNet, WorldFIP, and Interbus, among many others. There are commercial control valve actuators manufactured by most of the process control automation suppliers for Foundation Fieldbus and Profibus. If you pick one of these networks for your plant, then any actuator supplier that conforms to these standards can be used even if the other network connected instruments are from different suppliers. This is the power of standards. For discrete parts manufacturing and other binary two-state sensors and actuators using in a variety of industries, there are only a few "sensor networks" that extend all the way down to the limit switch, proximity switch, solenoid valve, and a few other sensor devices. DeviceNet (ODVA) and ASi (AS-interface) both use network nodes that interface to either four or eight devices using pre-wired cordsets to simplify installation. Interbus has an interface for ASi-connected nodes. There are some European standards for these sensor networks, but no international standard. The powerful unifying force is the "Open" nature of these networks supported by a membership association of many manufacturers sharing the common specification. These form de jure standards, or standards in fact. Interoperability is assured since suppliers that claim to conform to the specification must submit to formal testing. If you pick one of these sensor networks for your plant, any manufacturer claiming to support that network will be able to supply verification that their devices have passed the conformance tests. Now, back to the original question: in process control, you will find many actuator manufacturers that support both Foundation Fieldbus and Profibus. For discrete actuators, usually solenoid valves or power relays, many manufacturers will support the same device for DeviceNet and ASi. There are also many suppliers that only support one network. |