Here is a concise summary of the provided text:
**Overview of PLCs (Programmable Logic Controllers) and DCSs (Distributed Control Systems)**
* **PLC**: A ruggedized computer for automating discrete processes, originally designed by Dick Morley in the 1960s for GM to replace hardwired relay systems. Typically programmed using Ladder Logic.
* **DCS**: A system with multiple autonomous controllers distributed throughout a plant, introduced in the 1970s. Offers integrated monitoring and control, function block programming, and robustness against single-point failures.
**Key Differences (Historical Context vs. Today)**
* **Historical**: DCS was preferred for large plants with continuous processes, while PLCs were used for discrete controls.
* **Today**: Both systems have converged in capabilities, with PLCs now able to communicate over networks, offering similar robustness to DCS. However:
+ DCS advantages: lower installation costs, onboard monitoring and control.
+ DCS drawbacks: scarcity of programmers with specialized experience.
+ PLC advantages: more available programmers, flexible programming languages (e.g., Function Block, Sequential Function).
**Takeaway**: Both PLC and DCS systems can control an entire plant. The choice between them depends on weighing advantages, disadvantages, and system costs.
Here are the extracted key facts, each with a number and in short sentences:
**General**
1. A PLC (Programmable Logic Controller) is a ruggedized computer for automating processes.
2. A DCS (Distributed Control System) is similar to a PLC but has multiple autonomous controllers.
**History**
3. Dick Morley created a draft for a programmable controller in the late 1960s.
4. Morley's company, Bedford Associates, later became Modicon after finding financial support.
5. General Motors (GM) contracted with Modicon to purchase over $1 million in PLCs.
6. The term "Logic" in PLC was added with the advent of personal computers (PCs).
7. Modicon was acquired, with the latest owner being Schneider Electric.
**PLC**
8. Initially, PLCs were used for discrete controls, primarily replacing hardwired relay systems.
9. Early PLC programming was mainly in Ladder Logic, similar to a schematic.
10. PLCs receive device information, solve logic, and energize outputs to produce a desired effect.
**DCS**
11. DCS systems emerged around 1975, utilizing microcomputers for scalability, robustness, and security.
12. DCS allows an entire plant to be connected and controlled via proprietary communications.
13. Autonomous controllers in a DCS minimize the impact of a single controller failure.
**Comparison and Modern Developments**
14. Today, PLCs and DCS are quite similar, with PLCs often using open-source communications.
15. Modern PLC systems can communicate with each other, similar to DCS.
16. PLC systems require creating a separate Supervisory Control and Data Acquisition (SCADA) system.
17. DCS has an advantage in installation costs due to the location of autonomous controllers.
18. DCS programmers are scarcer due to the need for specialized experience in database functions and IT networking.
19. PLC systems have more available programmers, especially with new programming languages.