Connecting control systems to the Internet

Relatively few industrial control systems are currently web-enabled, even though the advantages are clear to see. However change is in the air as new technologies and new confidence reach the market, believes Jeremy Shinton of Mitsubishi Electric:

Hatfield, UK -- Technology to connect a control system to the Internet has been available for some years but to date its take up has been limited, both in terms of the number of installations and capabilities accessible over the ‘net.

A deciding factor has been one of user confidence, which is not necessarily measurable on a rational basis. For instance, it could be argued that the 9/11 terrorists attacks have held back take up of the concept – while these did not involve hacking into control systems via the Internet, there was a measurable upsurge in the fear of security breaches into sensitive systems that spilled over into the industrial and commercial worlds.

The connection of automation systems to the Internet has been via Ethernet adaptors to a web server or PC connected to the web. However the latest generation of PLCs have fully integrated PC modules available directly within the PLC racks.

With PLC-based systems gaining ground in the market, and with users now familiar with the convenience of Internet and web access thanks to their home computer set-ups, there has been an upsurge of interest in web-enabled control systems.

Web-enabled field devices are already commonly used to connect to ‘in-house’ intranets, where ‘in-house’ can be company-wide or restricted to a single physical site. Significantly access is usually restricted via password, key or biometrics to relatively few people, but the concept and advantages of remote access to data are being proven.

With thoughts now turning to full access over the worldwide web, potential installers are exhibiting commendable caution, saying they want access limited to certain people, to certain parts of the system, to read-only functions, etc. This is of course achievable and the way the developers intended that the technology should be deployed. Bespoke layers of security can be created for individual applications to prevent unauthorised access.

Advantages

A typical use of the web could be to create a secure and direct VPN connection to monitor load and recipes, or even modify programs within certain parameters.

Remote PLCs can collect and process raw data from local operations into business, maintenance or exception reports and email these to one or more central locations. Such PLCs can even use web-based messaging services to text maintenance details to an engineer.

One obvious use is plant and machinery maintenance. Many plants include inaccessible areas, or cover a large physical area or include remote outstations, where actual sight of the machinery is not practical. Instead sensors are used to monitor the machinery and send signals back to a central control room.

With maintenance engineers being readily mobile, it makes sense to have this data available on an intranet or the Internet so that assessments can be made promptly wherever the engineer happens to be.

This is attractive for simple maintenance tasks: for more involved decisions, such as those that would have serious a impact upon production, require a notable financial outlay, could involve safety considerations, have commercial ramifications, the advantages is that all necessary senior personnel can view data and therefore make informed decisions.

If the production control system is integrated with commercial systems, it becomes possible to optimise production schedules in real time, relating to order input and raw materials availability. This would simultaneously improve machine utilisation, supply management and overall production efficiency. It would also improve customer service in that clients could be kept fully up to date with the progress of their order.

Financial control of an enterprise can be enhanced because work in progress can be analysed in real time. This will highlight bottlenecks and where money is being unnecessarily tied up.

In conclusion, it seems likely that web access to production and/or enterprise control systems will become increasing common over the next few years. The technology to do this is already available and users are now confident that issues such as security and integrity can be guaranteed. Five years from now we will probably wonder why we were so reluctant to connect to the web.