Ethernet technology has now become ubiquitous in the offices and cubes of commercial business enterprises, and high-speed networking is becoming increasingly common in the home through a variety of consumer devices such as PCs, routers, switches, and wireless hubs. Are these commercial and consumer devices suitable for the industrial environment of the factory floor? Should the plant engineer grab a corporate credit card and head to a discount PC outlet?
Absolutely not. No self respecting plant engineer would put consumer hardware on his factory floor. But what exactly is the difference between consumer/commercial technology and its industrial counterpart? After all - in some cases they are functionally equivalent. For instance, the behaviour of an Ethernet hub from the local PC and peripheral supplier is not functionally different from that of a more expensive industrial hub from an industrial automation supplier. So why is it so important to use industrially rated hardware when networking industrial enterprise?
Industrial ratings
Most industrial ratings can be broken down into three principal categories: environmental, safety, and electrical. To ensure long-term reliability, interoperability, and performance over all conditions, these ratings are critical. With heavy equipment producing electrical noise, vibration, and potentially hazardous voltages, hardware installed in an industrial environment must be designed from top to bottom to perform reliably in these adverse conditions.
Reformulated technology
The new generation of industrial hardware takes full advantage of technology that has origins in commercial and consumer applications. In fact, this is one key advantage of using Ethernet as an industrial automation network. However, for industrial applications these core technologies have been reformulated for the more extreme demands of industrial applications. Here are some examples:
* Industrial Ethernet connectors (IEC IP environmental ratings).
* Industrial compact flash (wide temperature rating).
* Industrial Ethernet switches (EMC immunity, vibration).
Industrial controller versus PC
A consumer PC has no place on the factory floor. To obtain mean time before failure (MTBF) in the hundreds of thousands of hours, every component in the circuit must be scrutinised before it is included in the design. Unnecessary luxuries such as keyboard, mouse, and spinning hard drive are usually discarded or replaced with industrial grade equivalents, such as industrial Compact Flash for non-volatile storage. The Ethernet port replaces the keyboard and mouse, and serves as a high-speed link for downloading application code, performing run-time debugging and probing, and transmitting control and indicator values to a graphical user interface (GUI) running on a networked PC.
Embedded control
Embedded applications may be developed on a Windows host computer using an intuitive development environment with built-in functions for control and datalogging. The completed application is then downloaded over the Ethernet network for realtime embedded execution on an industrial controller. Embedding the application on a reliable, industrially rated hardware target with realtime performance, ensures successful operation even during any interruption of the network link.
Intelligent control I/O
An example of this industrially rugged control architecture is National Instruments' Compact FieldPoint. With this industrial control and measurement system, users may connect their sensors and actuators directly to high-accuracy analog and discrete I/O modules. The I/O modules filter, calibrate, and scale raw sensor signals to engineering units. The intelligent controller interface automatically publishes measurements over a standard Ethernet network. Once deployed, users can access the realtime application through any Web browser by connecting to the embedded Web server of the industrial controller. (For more information, visit ni.com/info and enter incfp.)
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