Connecting to a computer

A biochemical engineer with a little knowledge of electronics and computer interfacing can develop a system for bioprocess control at a relatively low cost. The sensors themselves tend to be expensive, but connecting them to a computer is usually easy. The computer must have an analog to digital converter (except when each sensor already does the conversion), and the engineer must amplify or reduce the signals from the sensors to match the voltages of the A/D converter. Devices that are set by the computer and that control the process are not expensive and are easy to construct.

Building amplifiers, wiring the system, and writing computer code take time. Mixing commercial components with home-built devices can save time but increases hardware costs. There is a trade off between labor cost and buying devices. While experienced engineers may develop a system in a few months, most graduate students take a year or more. This can be a great learning experience, but an equivalent or better system can be purchased and installed in about one month.

One very good and popular system is LabView ( see website www.natinst.com/labview ). This is a software package that is supported by hardware for data collection and process control. The software is configured to the hardware and leads to excellent data display. The data can be stored in computer files automatically or under control of the operator. Connections can be wireless by using the internet for the remote devices and the computer. Adjustmebts of set points and control of pumps and other devices are controlled by the computer. Strict security is essential to avoid terrorism and hacking, and good habits with passwords are essential.

RPI is very fortunate that an alumnus is a founder of National Instruments Company that developed and distributes LabView because we have an unrestricted site license that lets all professors and students have a free copy of the program. However, it is fairly expensive. A competing system called Wonderware is recommended by other professors as being less expensive and more accommodating to sensors and controls of companies other than National Instruments.

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