Why Use Ethernet Cable in Industrial Applications
A high demand exists in the industrial environment for the Ethernet family of computer network technologies for automation and process control. By using standard Ethernet, automation systems from different manufacturers can be interconnected throughout a process plant. Industrial Ethernet takes advantage of the relatively larger marketplace for computer interconnections to reduce cost and improve performance of communications between industrial controllers.
Some of the advantages of using Ethernet as the link-layer protocol over one of the open or proprietary protocols such as Modbus®, Profibus®, CANopen™, DeviceNet™, and FieldBus® commonly used in conjunction with PLCs (Programmable logic controllers) are:
• Increased speed, up from 9.6 Kbit/s with RS-232 to 1 Gbit/s with Gigabit Ethernet over Cat5e/Cat6 cables
• Increased distance
• Ability to use standard access points, routers, switches, hubs, and cables, which are immensely cheaper than the equivalent serial-port devices
• Ability to have more than two nodes on link, which was possible with RS-485 but not with RS-232
• Peer-to-peer architectures may replace master-slave ones
• Better interoperability.
However, moving Ethernet from an office environment into the industrial world is not as easy as one might think. The office environment offers its cabling system a relatively safe harbor, whereas industrial applications are often subject to harsh and hazardous environments.
A typical Ethernet cable construction is shown above. The cable consists of either two or four twisted pairs surrounded by a metal shielding (for shielded cable only) and covered by a jacket. For Cat6 and above, a cross-filler is often used as well. To learn more about the industrial Ethernet cable construction process, check out this whitepaper.