Intrinsically Safe Ethernet

Ethernet is now established as the preferred network for business and control layers in industry. In factory automation and the power industry it is rapidly being established as the device level network of choice. However, in process automation many different methods are used to power and communicate with end devices including 4-20mA, a variety of different fieldbus standards and serial communications including RS232, 422 and 485 with many different protocols. Ethernet communication between controllers and I/O subsystems is also extending beyond the control cabinets onto the plant floor. Remote I/O applications together with requirements for video and telephone communication are also taking Ethernet into process areas.

The deployment of Ethernet into process automation has been hindered by the gas or dust hazardous area classification in which the end device is often installed. The high installation costs of the mechanical protection methods required to install general purpose Ethernet in hazardous areas, together with the maintenance limitations, have reduced the uptake of both wired and wireless Ethernet. Many end users prefer to use intrinsic safety for low power hazardous area applications, such as instrumentation, having made significant investment in training their design, installation and maintenance staff in the technology.

IS Ethernet is now being adopted for communications across hazardous areas using copper for short distances and fibre for long distances. It provides WLAN infrastructure for the mobile operator using Intrinsically Safe mobile computers and tablet PCs, reducing installed cost and simplifying architecture with IS serial devices and providing automation infrastructure in coal mines. Importantly, the availability of these products allows device manufacturers to build IS Ethernet devices to deliver the benefits of open connectivity.