The DCS is being transformed into distributed computing platforms with enough performance to support real-time applications in large scale to address applications escalabies small units. Open systems standards are enabling DCS i receive information from different sets of similarly compatible computing platforms, including businesses, laboratory information, maintenance and other plant systems, as well as giving information to these systems to support multiple applications.
The traditional DCS are organized into five major subsystems: operational workstations, control subsystems, data collection subsystems, subsystems and process computer networks.
Foxboro DCS FCP270 Processor I / A Series
WORKSTATION OPERATIONS
The primary was the first workstation operator acceptance. Using mimic panels, easily understood by the operators was the first approach. This was done to emulate conventional instruments like the interaction you would with real instruments, with the advantages of both operational and economic. Charts were then added processes so pictorially represent a process unit or section of a process area of this updated information.
Alarm management is something that concerns the operations staff, regardless of the display you are watching, the current systems alert the operator to allow the boundary conditions of many process variables controlled in various ways both visual and audible. Providing information about trends in process conditions, is an area where the DCS has been developed in excellent shape, both the presentation itself of these, such as the ability to store information on thousands of variables, allowing to analyze in any time to improve the stability of processes, plant operations, inventory management, etc.
As workstations or workstation operations. operator evolved, the concept of universal workstation came into use. This is an operations console that provides all the information required by operators for both the regulation of processes such as access to selected information on other operations so as to allow the operator to make better tactical decisions such as when starting a unit or adjust Aigun a process for compensating the same problem.
The appearance of windows oriented workstations (Windows), essentially have allowed them monitors have screens divided into sections scalable, performing each of these sections as a separate display subsystem. Supervisors and operators can then view information from different programs simply directing the display sauda for that program to the windows partition, an operator may require a graphics processing unit 'process and view it in a first window, a statistical analysis of the last batches (lots) made in that unit led to a second window, a report of inventory of raw material available in third, the time trend area! specific variables in one quarter, the formulation or batch recipe running in fifth and summary of the production program of the week in sixth.
Command Center Foxboro, keyboards Operation Functional
If designed properly, several stations in different locations can simultaneously view the same information. In fact, they all can be made to independent and total access to all information and applications on the network.
Control Subsystem
The first multi-loop control was developed in 1970 by the firm Honeywell. He was 8 ties offered several features and flexibility, regardless of the setting of each control element, or blocks, but with the limitation on the ability to connect several blocks together to achieve complex control schemes without external wiring. This has been overcome in later years with subsystems larger in size and function, allowing the use of these drivers "shared" is the main reason for the use of DCS on conventional instrumentation.
Figure 4 - Physical structure of a DCS controller for all control loops share a number of cards
Figure 5 - Physical structure of a DCS controller which have individual cards for each loop
The tool to achieve this is the emulation of electronic instruments such as function blocks, which can be interconnected to form loop control strategies. The subsequent inclusion of interlocking functions and allowed secuenciarniento advanced control strategies; blocks typically include:
Blocks being relatively easy to use, however, are the result of a fairly complex design. Ai apply, it is important to understand that there are fundamental differences between your implementation using analog electronic circuitry or digital technology as for example with the sampling time of data synchronization algorithms in sequential applications, initialization of the blocks to use, response a1 these abnormal situations, procedural languages, etc..
Figure 6 - In a single module has all the capabilities
Renundantes FCP270 Processors (Foxboro)
Figure 7 - One of the characteristics of a system is redundancy. Here, each standby controller card is shared among active drivers
Figure 8 - Redundancy with a backup controller for each active controller
