PLCs send pager alerts via the Net

You could soon find your mobile phone ringing you whenever there is an alarm in your plant. This follows the development by Siemens of a pair of communications processors that can send text messages to a mobile phone, pager or email system if there is a plant emergency or equipment failure.

The processors, designed to work with Siemens` Simatic S7-300 and S7-400 programmable controllers, send alarm messages automatically via the Internet. Once a plant engineer receives the warning message, he or she can use a Web browser to access the PLC and perform an initial diagnosis of the problem.

The processors act as Web servers, storing pages of information about the control system which can be called up on any Internet browser (subject to security controls). "It allows you to visualise a plant without needing full-blown Scada," says Ray Smith, Siemens` controls systems product support specialist.

The two-way communications link will also allow systems integrators and developers to interrogate control hardware during configuration trials, and operators to access operating data without being on site.

Siemens has also enhanced its Simatic WinCC Scada package to support operator control and visualisation over the Internet. Plant operators can use it to access data from fieldbus-linked control systems and to modify operating parameters via the Internet. Siemens says that Version 5.0 of WinCC will open up new possibilities for plant management, especially where remote sites, multiple manufacturing centres or distributed control are involved.