PLCs are definitely changing. At the low end, in the sub-$1,000 price range, nano and micro-PLCs are gaining capability and offering lots of bang for the buck. At the high end, PLCs are becoming more like PCs every day. Sales are soaring and PLCs are here to stay.
Commenting on present market conditions, ARC Advisory Group (www.arcweb.com) says, "The industrial PC is not yet a threat," although they continue to hint at the faint possibility that somewhere, somehow, PCs will prevail. "Rapid changes in computing and communication technologies, a strong user acceptance of open systems, the global economic slowdown, and a small but growing threat from industrial PCs are combining to create turbulent market conditions and the threat of an uncertain future."
In spite of this doom and gloom attitude, ARC predicts that the total business worldwide for PLCs will increase from $5.8 billion in 2003 to $6.5 billion in 2006.
PLCs have certainly responded to ARC's "rapid changes in computing and communication technologies," and now fit right into open systems and networking. "One of the trends is that PLCs continue to have simplified programming," says Giardina. "You're seeing the continued expansion of programming languages and the simplicity of network setup."
Rockwell agrees that new opportunities are opening up. "One of the greatest opportunities for PLC growth is in safety control," says Miclot. "Today's safety PLCs are being utilized across a growing number of failsafe applications that were previously supported by safety relays. Safety PLCs can significantly reduce wiring costs and panel space as well as provide improved flexibility and reliability."
The PC-like capabilities of modern PLCs make some market researchers and suppliers want to change their name. "The term programmable automation controller (PAC) emerged to better describe a new breed of controllers that converge the best attributes of the PLC, DCS, PC, and open control platforms," says Miclot.
We continue to resist using that name to describe PLCs, but must admit that the nature of the PLC business has certainly changed. While nano and micro-PLCs continue to do traditional sequential logic work, their new capabilities let them compete in many other applications.
Higher-end PLCs are now doing tasks that once belonged exclusively to process control systems, such as DCSs. With their open PC architectures, PLCs are talking to business systems, such as ERP and asset management. And new PLCs are beginning to introduce even more capabilities, such as web servers, Ethernet communications, fieldbus connections, and HART.
You can see some of those new capabilities in the roundup products that follow:
