PACE 60-year Anniversary Series: Networking and communications
Industrial automation has come a long way since the mid-20th century when ‘communications’ referred to pneumatically-controlling remote systems via a centralised control base.
Though these technologies are still very common, today’s discipline of ‘industrial networking’ encompasses a much wider berth of new and improved communication topologies, allowing higher signal speeds, more reliable connections, and increased access to critical data from both the plant floor and the enterprise.
In today’s increasingly computerised factories, it is much more common to bring together traditional automation engineering with corporate IT, in order to gain a higher-level view of how industrial networking performance – and therefore process performance – can be improved.
In the 1960s, when digital computers and controllers began to make their way in to manufacturing and processing environments, many of the existing pneumatically-controlled systems were replaced with digital transmissions using proprietary networks.
With the advent of the microprocessor in the 1970s, distributed control systems (DCS) started gaining widespread popularity as many businesses turned to hierarchical forms of control.
Around 10 years later, local area networks started to become a common way to connect computers with industrial automation systems, which today can be seen in a growing number of manufacturing and processing plants in the forms of fieldbus, ethernet and wireless communication standards, to name a few.
Industrial ethernet
Daanet senior consultant – automation, electrical and networks, Mark Elrick, began working around the processing and automation industries in the mid-1980s; though local area networks had started to gain traction, many sites still relied on more traditional forms of control.
“At that time, there were mainly point-to-point connections between devices and controllers – few pieces of equipment were networkable,” he told PACE.
Elrick’s first job in the field was an Indentured Traineeship at Australian Iron & Steel in Port Kembla (later purchased by BHP), from 1982.
“After 10 years of hands-on maintenance and project engineering roles, including a significant role in the Hot Strip Mill (HSM) upgrade in the mid-80s, I moved to a contract management role in water treatment, where systems tended to be smaller, single controller-based with hard-wired interlocking where a network would now be employed,” he said.
An enclosure using EtherCAT fieldbus, an open, high-performance, ethernet-based fieldbus system for control automation technology, allowing short cycle times and low bandwidth utilisation. (Image courtesy of Beckhoff Automation.)
Elrick recalls the programming of PLCs on the mid-80s HSM upgrade was via a bulky dedicated programming workstation with a tape backup.
“Individual serial connections from each PLC were run to a patch panel in the engineer’s workspace of each local control pulpit, with uplinks joining the three pulpits. Any PLC could hence be accessed from any location through manual patching, much like an old telephone exchange. It would be another few years before PCs became commonplace as programming terminals, using networks like Data Highway with expensive interface cards,” Elrick explained.
For Elrick, the biggest development in networking and communications technology during his working career has been the introduction of industrial ethernet, which lead to the opening of connections between vendor-specific equipment.
“The old mantra from automation vendors was, ‘own the network, own the customer’. It was a strategy to get the customer locked into equipment with a proprietary or specialised network (DH, DH+, Profibus, etc), and they could never stray without pain,” he said.
“The major change is the development of ‘industrial ethernet’ in the 90s which then led to this quickly becoming the dominant industrial network. Open standardised protocols provide ease-of-interoperability between equipment that offers the same protocol – earlier generations did not see the same level of standards compliance.”
Elrick says today’s manufacturing and processing operations benefit a great deal from industrial ethernet, and the widespread migration from ethernet ‘hubs’ to ‘switches’ over the last decade has accommodated even larger networks with better performance.
“The ethernet port is a given as a PC interface, suiting both industrial and office networks, and eliminating the need for costly interface hardware. Ethernet has provided high-capacity networks, with 1Gigabit data rates now common – a multiple of some 20,000 times the common network rates of 15-20 years ago. This glut of capacity provides for network convergence, accommodating data and voice/video sharing the same cable,” Elrick explained.
“Field terminations of ethernet cables in both copper and fibre have become more common, reducing the cost of installation. Plus, ethernet network behaviour can be customised through the use of managed switches, introducing functions such as path redundancy, traffic prioritisation (say, ranking safety interlocks higher than general traffic), traffic filtering and real-time network diagnostics.”
Further, devices such as drives, instruments and managed ethernet switches provide status and diagnostic information directly to PLCs, appearing simply as an object in the IO tree – reducing discrete signal cabling and hence installation time, Elrick says.
“While ethernet-equipped PLCs were expensive or required a serial-to-ethernet interface module, the appearance of native ethernet ports in the bottom end ‘shoebox’ PLCs during the last decade has embraced distributed control, allowing micro controllers to look after localised functions, but still reporting to common supervisory systems, and interfacing with master control systems,” he said.
“Another development is the adoption of 802.11a/b/g/n standard wireless networks, providing a straight forward extension of the ethernet network, and accessibility using standard PCs (and more recently tablets and smartphones). These systems can take advantage of existing user authentication systems for security. Again, this replaced more limited proprietary wireless systems.
“The dominant theme of the development is the adoption of open systems – the exact antithesis of ‘own the network, own the customer’.
“Nonetheless, for short point-to-point connections, simple serial connections are still in use, but less and less as ethernet connectivity has become an essential basic function.”
Information and efficiency
Beckhoff Automation Australia and New Zealand managing director, Steven Sischy, started out in the process industry in 1990, before moving to specialise in factory and building automation.
Industrial ethernet is touted as making equipment such as programmable logic controllers (PLC) more interoperable; this industrial Ethernet switch increases the plant availability of your network.
According to Sischy, the first fieldbus networks to be deployed widely in Australia were RS-486 and ARCNET, however ethernet has since become more commonplace.
“Ethernet-based systems started to find their way into process and factory automation in 1990. The early adopters of ethernet technologies were Beckhoff Automation, Siemens, Mitsubishi Electric and Schneider,” Sischy told PACE.
“In 1990, I was involved in the installation and commissioning of a diamond mine and overland coal conveying systems. We deployed ethernet and RS-485 networks in the application.”
Though industrial ethernet is a relatively new technology, Sischy says it has allowed users to get more information and greater efficiency out of their machines and processes.
“Greater visibility and accurate measures on downtimes is now possible from anywhere in the world. We have seen the merger of some IT technologies into the factory automation arena and the net result is greater network speeds at a lower cost. Defined IEC standards will make sure vendors are developing technologies in accordance with the particular standard,” he explained.
“Most of the networks today are ethernet based. These networks provide greater security, deterministic packets, improved performance, ease-of-connectivity and greater diagnostics.”