Controls/software systems design

Engineered control A specific hardware or software system designed to maintain a process within safe operating limits, to safely shut it down in the event of a process upset, or to reduce human exposure to the effects of an upset. 

Software systems design is focused on developing the software architecture and requirements specifications. Similar to the electrical architecture, the software version is also known as a data flow diagram (DFD) that shows how different devices communicate with each other. For system with many devices, a separate communications architecture may be required. To design the software systems, a DFD is also created to map the data flow between sensors and mechanisms to the control units. In DFDs, there are boxes representing external entities or data sources, data flow shown as lines, data stores shown as open boxes, and processes shown as circles. 

A modular scanner system for NDE has been developed. It consists of a selection of individual electronics and motor module components, supported by scanner configuration and control software. The modules are used as standard building blocks for construction of job specific, dedicated scanners as well and general purpose scanners. The use of modular scanner components significantly reduce the work, time and cost not only for the design and manufacture but also for establishing documentation and ensure compliance with the relevant EU-directive requirements. 

Products in Group 3 seem to us to represent the future of practical batch process control. In such systems, modern workstations perform the single-user functions (e.g control system design, set-up, and maintenance operator interface data collection historical reporting) for which they were designed, while powerful multitasking controllers perform actual control. As computer hardware and software standards continue to evolve toward distributed networks of processors optimized for specific kinds of tasks, such systems will, we feel, proliferate rapidly. 

Software and computer systems that are subject to validation must be designed using strict procedures with sufficient documentation. During the process of system design, strict controls must be in place to allow future validation success. The system designer must ensure that documentation of the system meets minimum requirements necessary to satisfy the needs of the validation team. 

As seen previously for some specific applications such as wastewater treatment plants, software sensors can be envisaged to provide on-line estimation of non-measurable variables, model parameters or to overcome measurement delays [81-83]. Software sensors have been developed mainly for monitoring bioprocesses because the control system design of bioreactors is not straightforward due to [84] significant model uncertainty, lack of reliable on-line sensors, the non-linear and time-varying nature of the system or slow response of the process. 

The computer system attached to the instrument provides instrument control, data acquisition, data processing, and reporting. According to the draft Analytical Instrument Qualification chapter of the United States Pharmacopoeia (USP) <1058> The manufacturer should perform design qualification, validate the software and provide users with a summary of the validation. At the user site, holistic qualification that involves the entire instrument and software system is more efficient than modular validation of the software alone. Therefore the user qualifies the instrument control, data acquisition and processing software by qualifying the instrument. ... 

Two features of the complete system are worth stressing the autosampler design and its control and implementation with the specific software. TTie Touchstone software was designed by specialists in instrumentation with a great deal of experience of analytical chemistry. It uses computer techniques to give the analyst what is required, and it achieves its objectives easily and reliably. It is also easily understood by people who are not computer specialists. 

Operating system code availability Software/hardware specifications Software/hardware design practices Product design records Program coding standards System development records System test records Programming tools Control of nonoperational software Removal of dead code ... 

In addition to the machine guarding, the control system should be interlocked with an electronically monitored failsafe system. The control software should have an awareness of the position and action of all moving parts and measurement devices. Therefore, if an unplanned incident or out-of-protocol action does occur, the system will take action or stop action to minimize the likelihood of additional safety hazards. In some cases, as with system calibration or super user access, graded access levels can be custom-built into the design for specialized and infrequent operations. 

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