Implementing modern industrial application can present a challenging and sometimes daunting mix of requirements. For instance, it is well understood that a typical control system must interface with signals from simple actuators and sensors, yet for many modern applications this is merely the starting point. Advanced control features, device interoperability, network connectivity, and enterprise data integration are all capabilities demanded increasingly in a modern industrial application.
These modern requirements extend far beyond the traditional discrete logic based control input/output signals handled by a PLC (programmable Logic Controller). Most PLCs are programmed using Ladder logic diagram, which has its origins in the wiring diagrams used to describe the connections and layouts of discrete physical timers and relays in a control system. Applications that expand beyond or diverge from this model become increasingly hard to program in ladder logic. For instance, mathematically complex applications such as proportional integral derivative (PID) loops used for temperature control involve floating point arithmetic. PLCs must often be enhanced with separate hardware cards.
Using a PLC to meet modern application requirements for enterprise data integration device interoperability, network connectivity presents other challenges. These type tasks are usually more suited to the capabilities of the computer. To provide these capabilities in a PLC application additional processor, network converters or gateways, middleware software running on a separate PC, and special software for enterprise systems must often be integrated into the system.
In other word, a PC packaged for industrial environments can provide many capabilities sought in modern applications, particularly those needed for the networking and data communication. Similar to augmenting a PLC to accomplish PC like tasks, however, an industrial PC that needs to perform PLC like tasks such as machine for process control. For instance, a PC may be using an operating system that is not optimized for high performance and deterministic industrial applications.