Industrial network protocols include EtherNet/IP, Ethernet Powerlink, EtherCAT, Modbus-TCP, Profinet, SERCOS III, and the list is still growing. How do you select an industrial network protocol that is future-proof and meets your unique requirements?
In the beginning, factories contained a labyrinth of mechanical linkages. Through marvels of mechanical engineering, they were optimized to improve factory output. Then someone replaced a few linkages with electronics to herald a new era for manufacturing control.
Point-to-point wiring created new complexity, and was quickly replaced with a field-bus approach. Many manufacturers now implement hybrid Ethernet and field-bus networks in and between factories, to interconnect devices ranging from small hand-held controllers, assembly robots, programmable logic controllers, to large data storage nodes and centralized operations control centers.
During this evolution, industry created its own unique approaches and protocols to solve its own unique problems. However, industrial network protocols are rapidly converging and adopting ideas from other areas, such as telecommunications and networking.
Where historically these groups would never meet, they now collaborate to share the best network and control technology across different applications. We are starting to see the same network protocols used for critical applications as diverse as power system management, hospital system integration, and wiring harnesses in aircraft.
Unique Industrial Problems
Many applications share attributes which make them ideal candidates for standard network protocols running on embedded network systems:
- Real-time operation means that state changes are detected and appropriate actions are carried out within an acceptable timeframe.
- Deterministic operation means instructions are executed in a predetermined order and at a predetermined time.
- Reliable operation usually means the system has N+1, 2N or N+M redundancy, depending on the perceived cost of an outage.
- Secure operation means that unauthorized persons cannot accidentally or intentionally access or change data and manipulate control systems.
- Safe operation means the system will not harm people or nearby equipment.
- Ruggedized operation means the system can operate in harsh environments such as:
o -40 C to 120 C temperatures at each chip on a board
o Locations that are dirty, dusty or surrounded by dangerous chemicals or emissions
o Environments that contain high levels of electromagnetic radio emissions across a wide frequency spectrum
o Remote systems which are difficult to access for maintenance and repair. These systems require designs that minimize parts with higher failure rates, such as fans, to reduce time between system-level failures
o Systems that are operated by people who are not necessarily technology experts, who may not have access to sophisticated diagnostic equipment, and who often do not have time to read a long instruction manual or take a training course.
Why create unique Industrial Network Solutions?
The cornerstone of interoperability is a standard communications protocol. At first glance, standard Ethernet might seem a perfect solution for industrial network communications because it is an open, proven, cost-effective, world-wide standard that's easy to implement and use.
It supports 100 to 1000 megabit per second data rates which are orders of magnitude more bandwidth than most existing industrial field buses. Internet protocols provide integration and data transparency on all networking levels and they allow data to move easily from factory floor into back-room systems for management and control.
However, Ethernet alone is not sufficient to support the complexities of industrial networks. Even though standard Ethernet protocols define communications from the physical hardware layer to the communications application layer of a network, they do not include user application levels e.g. the data formatting to enable data exchange between equipment.
Industrial consortia are establishing additional protocol layers to enable this equipment interoperability. However, as these protocols develop, industrial customers are becoming increasingly cautious about proprietary systems and they want to avoid unpredictable dependence on any one system vendor.
An extensive range of applications can benefit from Ethernet-based industrial network protocols, such as:
-Building Automation, Control, Security
o Smoke/Heat detectors
o Fire Alarm Sounders
o Fire Alarm Control Panels
o CCTV Cameras and Control Panels
o Intruder Alarm Control Panels
o Intruder Alarm Motion Detectors
o Access Control
o Biometrics Security Systems
o Carbon Dioxide Detectors
-Factory, Power, Food Automation
o Motion Controllers
o Machine Vision
o Operator Panels
o Embedded Computer Boards
o I/O Modules
o Industrial Networking Products
o Process Controllers
o Measurement Equipment
- Aerospace, Defense, Robotics
o Image processing
o Control Processing
o Data acquisitions
o General Purpose processing
- Health Care
o Health Care Imaging
o Home Health Monitoring
o Patient Monitoring
o Dialysis Machines
o Cardiac Rhythm Management
o Hearing Analysis Equipment
o Powered Beds
Field bus protocols originally evolved for industrial systems, such as: Profibus, DeviceNet, ControlNet, CANOpen, InterBus and Foundation Field Bus.