The manufacturers of automation have responded to the modern industrial application’s increased scope of requirements with industrial control devices that blend the advantages of PLC style deterministic process control or machine with the flexible configuration and enterprise integration strength of PC based systems. Such a device has been termed a programmable automation controller (PAC).
While the ideal combining PLC and PC based technologies for industrial control has been attempted previously, it has usually been done through the “add on” type of approach described earlier, where additional processors, middleware or both are used in conjunction with one or more PLCs. A PAC however, has advanced capabilities needed built into the design. For instance, to perform functions like counting, PID loop control, latching, and data acquisition and delivery, a typical PLC based control system requires additional, and expensive, processing hardware. A PAC has these capabilities built in.
A PAC is notable for its modular construction and design, as well as the use open architecture to provide interconnection and expandability with other devices and business systems. PACs are marked both by efficient processing and I/O scanning.
Characteristic that industrial analyst ARC Advisory Group originated the term “PAC”. ARC coined the term for two reasons: to help automation hardware users better define their application needs, and to give automation hardware vendors a term to more communicate clearly their products capabilities.
A Programmable Automation Controller must fulfill the below requirements:
• Operate using multiple a single platform in multiple domains
• Employ a single platform of development using common tagging and a single database
• Tightly integrate controller software and hardware
• Be programmable using software tools
• Operate modular architectures that mirror industry applications, from machine layouts to unit operation in process plant
• Employ de-facto standards for networks interfaces, protocols and languages, allowing data exchange as part of the networked multi vendor systems
• Provide efficient processing and I/O scanning