A "Soft" DCS/PLC System Goes Live in South Africa

New System is One of First to Deliver PC-Based Open Control in a PLC Form Factor

Vendors of traditional distributed control systems (DCSs) and programmable logic controllers (PLCs) have gradually been converging with the PC software world over the past several years. At the same time, however, those software vendors have been building up the capability to run either a DCS- or PLC-style control system solely in the microprocessor circuits of a PC-the so-called "soft" DCS or PLC.

Now, NCP and Microlab (Johannesburg, South Africa) and AlterSys (Montreal, Canada) have completed one of the world's first "soft-DCS/soft-PLC'' control systems to run in a PLC form factor. Based on a real-time operating system (RTOS) from a company called QNX (Kanata, ON), Allen-Bradley Open Controllers, and Allen-Bradley Device Net technology, the new system allows operators at the NCP Food Acid Plant to take complete control of the plant's chemical process from any point in the factory-wide network.

"The plant managers at NCP wanted a single system that would integrate distributed data acquisition, realtime soft-PLC type automation, and a graphical HMI, as well as reporting, trending, and alarming,'' says Julien Chouinard, president of AlterSys. "And they wanted the system to be fully open, so that they could modify and upgrade it themselves.''

Microlab, the system integrator, needed software that would run in the Open Controller's 20M flash disk. QNX was a perfect fit, with its small memory footprint, realtime performance, and distributed IPC. Microlab then chose QNX-based PCPVirgo from AlterSys as the soft-DCS automation enabler. PCPVirgo's Single Image Model distributed realtime database uses the QNX virtual machine to transparently link the plant's entire network into a powerful DCS.

"With QNX's network-distributed IPC, every point in the I/O network becomes accessible from any Allen-Bradley Open Controller, resulting in a single logical I/O machine for the entire plant," says Greg Bergsma, senior technology analyst at QNX Software Systems. "Better yet, NCP can extend the DCS simply by plugging another Open Controller into the network-there's no need to change the application-level software.''

Miro Zaric, system design integrator at Microlab, says, "We haven't merely connected an HMI to a PLC. PCPVirgo is actually embedded in the Open Controllers, transforming them into a true open DCS. In addition, PCPVirgo enhanced our productivity through a powerful graphic screen builder and soft PLC languages such as Structured Text and Sequential Flow Charts.

Founded in 1980, QNX Software Systems develops high-performance realtime operating system software for PCs. With installations in over 60 countries, the company has established a firm base in process control, aerospace, telecommunications and other mission-critical environments.

For more information about the NCP installation or PCPVirgo, contact AlterSys, 555 D'Auvergne, Longueuil QC, Canada J4H 4A3 or 514-674-7774, by fax, 514-674-7344

For more information about QNX, contact QNX Software Systems Ltd, 175 Terence Matthews Crescent, Kanata, ON, Canada K2M 1W8 or, 613-591-0931, 800-676-0566, by fax, 613-591-3579