Controller personal computer controllers

The component controllers used in the controller subsystem portion of the DCS can be of various types and include multiloop controllers, programmable logic controllers, personal computer controllers, singleloop controllers, and fieldbus controllers. The type of elec tronic con-troUer utihzed depends on the size and func tional characteristic of the process apphcation being controlled. See the earlier section on distributed control systems. 

Personal Computer Controller Because of its high performance at low cost and its unexcelled ease of use, apphcation of the personal computer (PC) as a platform for process controllers is growing. When configured to perform scan, control, alarm, and data acquisition (SCADA) functions and combined with a spreadsheet or database management apphcation, the PC controller can be a low-cost, basic alternative to the DCS or PLC. 

Electronic Records and Electronic Signatures Considerations ERES compliance testing for computerized (personal-computer-controlled) instruments is required to demonstrate the functional requirements in the following three key areas [12-14] ... 

Data backup and restore Active data are periodically copied from the hard drive or the personal computer controlling the instrument to a suitable medium such as CD-ROM or DVD or to a separate location such as a controlled file server. 

Business Continuity Planning (Disaster Recovery) A disaster recovery plan should be in place to ensure the continued operation of the laboratory in case of an adverse event that renders the instrument out of commission and hence causes interruption to the business processes which the system supports. Adverse events like the failure of the critical hardware components of the instrument and the failure of the application software do happen in the day-to-day operation of a laboratory. The disaster recovery plan should provide the necessary steps to restore the systems back to a functional state. The steps typically include instructions to reinstall the application software to the personal computer controlling the instrument, to reconfigure the instrument, and to restore the backup data to the instrument. 

The Millilab 1A workstation is a personal computer-controlled automated robotic system which performs sample extraction from filters and SPE devices according to user-defined programs. This was used to compare the efficiency of different SPE materials, as manual error is substantially reduced. The results are listed in Table 26.1. 

A fully automated, personal computer-controlled spotter (e.g., the Camag Automatic TLC Sampler III), which consists of a stainless steel capillary connected to a dosage syringe operated by a stepper motor, can sequentially apply constant or variable volume samples, chosen from a rack of vials, within the range of 10 nl to 50 pi as spots or bands. 

ENEA (Comitato Nazionale per la Ricerca e per lo Sviluppo dell Energia Nucleare e delle Energie Alternative) in cooperation with CISE (Centro Informazione Studi e Esperienze) developed an advanced automatic corrosimeter for monitoring corrosion in power plants, consisting of two modules the first one acquires data from the probes, and the second one (an IBM personal computer) controls the first module and performs all the required calculations. Several probes can be connected to a single corrosimeter [12]. 

Different types of machine process controls (PCs) can be used to meet different requirements based on the molder s needs. PC systems range from the unsophisticated monitors (alami buzzes, light flash) to very sophisticated program controllers (personal computers (PCs) interrelate different IMM functions and melt process variables) (Figure 30). (Note that PC has different definitions see Appendix A, List of Abbreviations.)... 

A.3 Microprocessors and Digital Hardware in Process Control A.3.1 Single-Loop Controllers A.3.2 Programmable Logic Controllers A.3.3 Personal Computer Controllers A.3.4 Distributed Control System... 

A recent trend in particle analysis has been the introduction of personal computer-based automation (3). Sophisticated software packages can be used to automate and speed up the analysis. In some cases these computers can even carry out continuous process control (qv) (see Computer technology). The latest machines also allow the measurements of smaller particles and can detect a wider range of sizes. Machines based on light-scattering principles are being more widely accepted by the industry because of speed. An average analysis takes from 1—2 min, whereas those based on sedimentation principles require from 10—120 min. 

Stand-alone computer systems, usually based on a personal computer (PC) or programmable logic controller (PLC), provide a separate computer system for each pilot plant. This allows for economical expansion for new units, separates pilot plants completely for maintenance and troubleshooting, and often has the lowest initial cost. Standardization can be a problem and software control, data gathering, and storage packages can be limited in size, scope, and capabiUty these are usually acceptable trade-offs. 

Single-loop controllers provide both the process control functions and the operator interface function. This makes them ideally suited to very small applications, where only two or three loops are required. However, it is possible to couple single-loop controllers to a personal computer (PC) to provide the operator interface function. Su(m installations are extremely cost effec tive, and with the keen competition in PC-based produc ts, the capabilities are comparable and sometimes even better than that provided by a DCS. However, this approach makes sense only up to about 25 loops. 

The team should have a wide range of knowledge and experience. If a contractor designs the plant, then the HAZOP team should include people from both tlie contractor and client organizations. On a computer-controlled batch plant, the software engineer should be a member of the HAZOP team, which should include at least one other person who understands the computer logic. 

Code suites are integrated collections of personal computer codes that perform different functions but work together through unified controls and data transfer. 

FTA, fault free analyzer module, uses SETS and FTAP to reduce fault trees and generate minimal cutsets for storage as minimal cutset libraries. Cutset control uses truncation hy probability or order. The user chooses the codes according to the personal computer s capabilities. The FTA module uses OR, AND, N/M, switch gates and supercomponents. 

RISKMAN is an integrated Microsoft Windows , personal computer software system for [H. i forming quantitative risk analysis. Used for PSAs for aerospace, nuclear power, and chemical [iroccsses, it has five main modules Data Analysis, Systems Analysis, External Events Analysis, Event Tree Analysis, and Important Sequences. There are also modules for software system maintenance, backup, restoration, software updates, printer font, and page control. PEG has also integrated the fault tree programs CAFTA, SETS, NRCCUT, and IRRAS into RISKMAN. 

When local or central computers are used for controlling the operation of HVAC installations in buildings, they are described as building automation systems. In the control station, operators communicate with control installations, which are connected through the computer plant. Computers for individual use are called personal computers (PCs). The use of PCs for technical and economic tasks in the past few years has increased considerably. The business overflows with PCs, which get greater data power and memory at lower prices. 

Schematic of a typical EMCS with local control modules, command control modules, and personal computer interface.

Personal computer interface simplifies operator control of the system through a user-friendly interface. 

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