In some plant automation applications, system designers move toward to PCs. This alternative presents the standard development platform appeal, familiar graphical user interfaces, accessible high-end software application, comfortable and standard programming languages. In manufacturing environments, though, PCs look consistency risks and development limitations. Addition a board can be hard and the results volatile. PCs are unknown for their behavior of deterministic real-time. The same vendors of PC hardware and software development that present low prices are not equipped to provide the support time or product long life that the manufacturing user requires. Hardware desktop is not charged for wide range of operating temperature nor rugged environments with shock, vibration, and high temperature gradients. There are numerous vendors of middle-tier hardware that are currently presenting standard PC, at realistic prices, but with rough specifications and support necessary for the plant environment. PCs are not tally for the mechanical straightforwardness and simplicity of hardware development that PLCs offer. Screw terminal, DIN rail hardware; fuses, and LEDs, hot insert these are a little of the PLC mechanical standard features not available readily on PCs.
Automatically, the flexibility benefits in GUI and software familiarity are at the cost of the rugged components and the mechanical side. The problems created by these two accepted PLC and PC for implementing cells of plant control are important, both affectation major inconveniences along with benefits. As a consequence, there has been development in developing a middle ground between the PC and the PLC, a shared solution that includes PCs into PLCs. In earlier cases, the PC was additional in, or secured on, or an interface was additional for cross-development to a PC.
A more than third current approach-- illustrated by the Open Controller family of Allen-Bradley is to in reality according the PLC on a foundation PC. The Open Controller has a dual backplane, counting a PCI bus all along with the bus of traditional PLC. While several aspects of the chassis are still proprietary, the most significant aspects the systems of standard operating and the PCI bus are open to third party value-added.
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PLC and PC
PLC and PC