Step outside the factory with Schneider Electric's control systems

Citation

(2001), "Step outside the factory with Schneider Electric's control systems", Assembly Automation, Vol. 21 No. 2. https://doi.org/10.1108/aa.2001.03321baf.010

Step outside the factory with Schneider Electric's control systems

Step outside the factory with Schneider Electric's control systems

Keyword Electronic control

Schneider Electric has put its proven Internet-enabled PLCs and Ethernet together with wireless application protocol (WAP) phone technology, giving its PLCs real-time access to the outside world (see Plate 6). So if you are in the airport and there is a critical deadline which needs to be met, you can check: have you achieved it? If you are away from your office you can alter the maintenance schedules after you have checked whether there are spares in stock for the work. If you are in a meeting when there is a critical machine failure, the control system will tell you when it detects the fault. As the PLC Web server can now be accessed by a mobile phone or similar wireless device, companies now have the freedom to manage plant and equipment remotely, the instant the need arises.

Plate 6 PLCs can now be accessed via a mobile phone, providing remote management of plant and equipment

Schneider Electric's transparent factory concept uses the Ethernet TCP/IP and the Internet to link groups of PLCs together and make it possible for control systems to work in close co-operation with business systems. Now the company has made it possible to step outside the factory yet still retain access to control systems by introducing WAP phone access to its PLC-based control systems. Control and monitoring of any process using Internet-enabled PLCs can be carried out over a digital cell-phone link, which means that the engineer can be in the next room, in the next town … or the next continent.

"It means you can now get performance and diagnostic data using just a Web browser", says Chris Holt, Automation Marketing Manager at Schneider Electric. "Instead of having to go to the SCADA system, you dial into a WAP gateway which after authentication connects you to the Web server in the PLC. Software in the Web gateway called 'servlets' reads information from the PLC and passes it out to the WAP phone. Similarly information can be sent from the phone via a 'servlet' to the PLC. And this happens in real time."

A servlet is the server-side equivalent of the applet, written in Java and portable between a selection of Web servers. The purpose of the servlet is to connect to the PLC and either update it from information it has been sent, or take information it reads and create a dynamic page which can be sent through WAP to the mobile phone. When logging in to the control system, the caller is asked for user name and password, and the calls themselves, being digital, are extremely secure. Should it ever prove necessary, additional levels of security are available within the servlet architecture.

As well as two-way communication between PLCs and the mobile phone, it is also possible for the control system to raise alerts in the event of equipment distress, service disruption or on a timed basis. This can be done either by sending an e-mail or by using the simpler mobile phone short messaging service (SMS), which will carry messages of up to 160 characters.

"This is not just relevant to process control systems in factories", says Holt. "Wherever control systems are used, for example, in building management, this principle can be applied. To turn off the lights or turn the heating down, here is open technology which will do that job. In the water industry it can be used by the engineering staff to monitor pump status, adjust settings and call out repair teams in the event of failure."

Schneider Electric customers will benefit from the freedom this gives them. It is now possible to monitor plant and equipment remotely, both for people who need to be in different locations yet still have control of production processes and for the many others for whom remote access to performance statistics would be a huge benefit. The applications to which this relatively simple technology can be put are simply limitless.

For further information contact: Chris Holt, Schneider Electric, University of Warwick Science Park, Sir William Lyons Road, Coventry CV4 7EZ, UK. Tel: +44 (0)1203 416255; Fax: +44 (0)1203 417517.