Ethernet for sensor networks? Why it makes sense today
Sensors are like the “scouts” of the manufacturing world; they collect vital information that keeps a manufacturing plant running effectively, efficiently, and with minimum waste, and they report it to the control system, preferably in time to take corrective action when things are trending awry. Today, thanks to Ethernet, sensors can provide their input on the “superhighway” of the plant floor, providing an effective two-way communication stream that can improve efficiency and profitability.
Sensors traditionally fed their information through wires back to a central location where the signals were decoded and acted upon. A plethora of fieldbus networks evolved that expanded the amounts and kinds of data sensors could communicate, such as complex measurements including pressure, level of a substance in a container or closed area, motion detection, and identification of specific patterns. The downside to this, of course, was the job of managing, maintaining, and training for multiple communication protocols.
Now industrial Ethernet is becoming the de facto communications protocol for plant applications. The argument for separate fieldbus protocols was always that Ethernet did not fully meet the needs of the factory floor. However, with the advent of deterministic Ethernet protocols and zero failover redundancy protocols, the need for a separate fieldbus for relaying sensor data has diminished dramatically. It is possible and desirable to deploy an integrated industrial Ethernet infrastructure that extends from the control center to the very edge of the network—the sensors.
Enclosure-less I/O blocks (also called distribution blocks) are the vehicle that supports running Ethernet all the way to the sensor. Enclosure-less I/O blocks can be installed close to the sensors, thus eliminating the logistics complexities of running single wire back to a central control panel for each sensor. Active (or smart) enclosure-less I/O blocks, supporting industrial Ethernet, enable two-way communications among the I/O block and programmable logic controllers (PLCs) or remote terminal units (RTUs).
An industrial Ethernet infrastructure facilitated by enclosure-less I/O blocks has the potential to provide significant manufacturing efficiencies and cost savings. Not only can it support control and safety functionality, but also data acquisition that can be used for tracking and traceability, asset management, historical records, and other operations and production needs. In addition, running industrial Ethernet all the way out to the sensors allows plants to be operated under one communications protocol, resulting in less hardware (and operational) complexity. By connecting sensors to industrial Ethernet via enclosure-less I/O blocks, the opportunities for reducing deployment and maintenance costs while increasing overall performance and reliability increase dramatically.
– Mike Miclot is the vice president of marketing, industrial solutions division, at Belden Americas Group. Miclot leads strategy formation and go-to-market planning and execution in support of Belden industrial cable products, as well as Hirschmann, Lumberg Automation, and GarrettCom brand solutions. Edited by Mark T. Hoske, content manager, CFE Media, Control Engineering and Plant Engineering, email@example.com.