Check out the Hard Real-Time with Windows XP article on Embedded Star. Phoenix Contact created a Soft PLC with the convenience of the Windows(R) XP interface on the user side, while at the same time providing hard real-time by utilizing the Windows(R) CE real-time operating system – all running on a single Intel XXX based computer. KUKA Controls’ CeWin(R) software was used to bridge the two operating systems. The article explains the advantages of Soft PLC over the standard embedded control PLC, and the criteria used by Phoenix Contact when implementing PC WORX.
So, why would anyone wish to choose Windows PC as a control platform with the functionality of a PLC? Afer all, just about everyone has had their pc blue screened at one time or another. The answer is simple. A Soft PLC offers the reliability of a standard embedded control PLC (dedicated hardware) on the one hand, while on the other, providing all the convenience and high processing capacity of a PC environment.
According to the article, KUKA Controls CeWin real-time extension platform is the key element which makes the new industrial PC solution able to operate in hard real-time. With CeWin, Windows XP can be operated on the same CPU in parallel with the Windows CE real-time operating system, without Windows XP negatively impacting on the ability of the system to operate in real-time.