Instrumentation minicomputer

A further advantage of spectrophotometers is the ready availability of a number of low-cost instruments with sufficient accuracy and reproductivity for dyebath analysis. Much of the work in the current study was carried out on a single-beam grating spectrophotometer costing approximately 2,000. The computations necessary in the analysis can be conveniently carried out on low-cost desk calculators or microprocessors. The calculations necessary for a four-dye mixture (or three dyes plus background) can be handled on a system costing less than 1,000. The least-squares fit of 16 points of the absorption spectrum can be carried out on a 3,000 minicomputer. Development of these low-cost instrument-minicomputer systems is largely responsible for consideration of dyebath reuse as a practical reality for the textile industry. 

The minicomputer based system for Instrument automation at Glidden has been prevlousj.y reported (1). since that system predates the availability of low cost personal computers and data acquisition hardware, most of the hardware and software was designed and assembled in-house. ... 

T.F. Niemann, M.E. Koehler, and T. Provder, "Microcomputers Used as Laboratory Instrument Controllers and Intelligent Interfaces to a Minicomputer Timesharing System," in Personal Computers in Chemistry> p- Lykos, Ed,... 

The labor-intensive nature of polymer tensile and flexure tests makes them logical candidates for automation. We have developed a fully automated instrument for performing these tests on rigid materials. The instrument is comprised of an Instron universal tester, a Zymark laboratory robot, a Digital Equipment Corporation minicomputer, and custom-made accessories to manipulate the specimens and measure their dimensions automatically. Our system allows us to determine the tensile or flexural properties of over one hundred specimens without human intervention, and it has significantly improved the productivity of our laboratory. This paper describes the structure and performance of our system, and it compares the relative costs of manual versus automated testing. 

It is interesting to trace the development of instrument automation over the relatively brief period of the past ten to fifteen years. Early in this period, a truly automated instrument was a rare and expensive item built around a costly dedicated minicomputer. Automated data collection and analysis from any instrument which was not automated at the factory was usually accomplished by digitizing the data and storing it on a transportable media such as paper tape. These data were then delivered and fed to a timeshare system of some sort on which the data reduction program ran and which printed a report and sometimes a plot of the data. Often a considerable time delay occured between the generation and the analysis of the data. The scientist was at the mercy of the computer elite who could implement his data logger and provide the necessary computer resources to analyze his data. The process was expensive, both in time and in money. 

This presentation demonstrates that a small minicomputer can be used to provide a full range of functions for collection and interactive reduction of data from a size-exclusion liquid chromatograph. A number of different users have collected in excess of 5000 chromatograms using this equipment. The experience gained with this system has influenced our approach to the automation of other analytical instruments. Careful attention to control paths, provision of "user friendly" access to the system functions, and careful management of the data archiving functions are crucial to the success of such efforts. 

The distinction between mini - and microcomputers is becoming essentially one of size and price. Minicomputers, which use 16- or 32-bit words, had much larger memories than microcomputers and could be used for the control of several laboratory instruments on a time-sharing basis. However, microcomputers are becoming ever more powerful. Although some still use 8-bit words, 16-bit and 32-and 64-bit word machines are becoming stan-... 

Additionally, use of a commercial AI shell for expert system development has been demonstrated without the need to learn computer programming languages (C, Pascal, LISP or any of its variations), nor to have an intermediary knowledge engineer. Although this development effort of 4-5 man months was on a minicomputer, adaptation of EXMAT to the microcomputer version of TIMM is anticipated. The completed implementation of EXMAT will support the belief that AI combined with intelligent instrumentation can have a major impact on future analytical problem-solving. 

The late 1960s saw the appearance of dedicated laboratory mini-computers and the third generation of instrument systems (Fig. 8.4). The computers were interfaced to existing instruments and were used primarily to log and process data. In some cases, simple instructions could be sent to the instrument by programs resident in the minicomputer. It was also possible for the computer to optimize instrument conditions in real time by monitoring output data. 

A Waters Model 150C ALC/GPC was interfaced to a minicomputer system by means of a microcomputer for automated data collection and analysis. Programs were developed for conventional molecular weight distribution analysis of the data and for liquid chromatographic quantitative composition analysis of oligomeric materials. Capability has been provided to utilize non-standard detectors such as a continuous viscometer detector and spectroscopic detectors for compositional analysis. The automation of the instrument has resulted in greater manpower efficiency and improved record keeping. 

There are four stages in an automated instrument analysis. In the first stage, the instrument operator initiates the experiment by means of dialog programs on the minicomputer. Examples of the dialogs for the HPGPC operation are shown in Figures 1-4. 

Before initiating an analysis, the instrument must be programmed for automatic operation and the samples placed in the appropriate positions of the injector. Dialog 16, shown in Figure 2, starts operation of the microcomputer. Intelink communication with the instrument is established and the parameters for the first sample are taken from the sample definition file on the minicomputer and are transmitted to the microcomputer. The microcomputer turns on a ready status light at the instrument to signal to the operator to begin automatic operation of the instrument. 

Niemann, T. F. Koehler, M. E. Provder, T. "Microcomputers used as Laboratory Instrument Controllers and Intelligent Interfaces to a Minicomputer Timesharing System" in "Persona] Computers in Chemistry" Lykos, P., Ed. John Wiley and Sons New York, 1981 pp. 85-91. 

The automation of the HPGPC/Viscometer system is achieved by interfacing the differential refractometer (DRI) and viscosity detector to a microcomputer for data acquisition. The raw data subsequently, are transferred to a minicomputer (DEC PDP-ll/HiI) for storage and data analysis. Details of the instrument automation are given elsewhere.(6)... 

Portable valve-regulated lead-acid cells can operate in any orientation without acid leakage and find use in many different applications, such as in electronic cash registers, alarm systems, emergency lighting unit equipment, telephone boxes, switching stations, minicomputers and terminals, electronically controlled petrol pumps, cordless television sets and portable instruments and tools. 

The chromatographer can choose from an enormous range of commercially available instruments (2). Some rather simple devices can be purchased for a few hundred dollars, whereas" a turnkey minicomputer system designed to collect and process data from a half dozen or so chromatographs operating simultaneously will cost tens of thousands of dollars. The field is changing too rapidly to discuss manufacturers, models, and features in any detail. 

Three types of computer control systems are commonly used for pilot-plant instrumentation. The first is a centralized system, usually based on a minicomputer or occasionally a mainframe. These systems have large storage capacities, substantial memories, and much associated equipment. They typically control all the pilot plants in an area or facility. Centralized systems are economical if a large number of units are involved but are becoming less common due to their high installation and maintenance costs as well as the limitation that any failure of the central system shuts down all pilot plants involved. 

At task complete, the Fortran programs in the larger computer process the result and determine the course of the experiment. Getting a piece of information measured on the diffractometer is functionally similar to calling a subroutine which returns after the information is available. An alternative way to achieve the same flexibility is to build up the instrument control minicomputer into a much larger system. 

Since the article by Spedding1 on infrared spectroscopy and carbohydrate chemistry was published in this Series in 1964, important advances in both infrared and Raman spectroscopy have been achieved. The discovery2 of the fast Fourier transform (f.F.t.) algorithm in 1965 revitalized the field of infrared spectroscopy. The use of the f.F.t., and the introduction of efficient minicomputers, permitted the development of a new generation of infrared instruments called Fourier-transform infrared (F.t.-i.r.) spectrophotometers. The development of F.t.-i.r. spectroscopy resulted in the setting up of the software necessary to undertake signal averaging, and perform the mathematical manipulation of the spectral data in order to extract the maximum of information from the spectra.3... 

The transform from the interferogram to the spectrum is carried out by the dedicated minicomputer on the instrument. The theory of Fourier-transform infrared spectroscopy has been treated, and is readily available in the literature.21,22,166 Consequently, the advantages of F.t.-i.r. dispersive spectroscopy will only be outlined in a qualitative sense (i) The Fellgett or multiplex advantage arises from the fact that the F.t.-i.r. spectrometer examines the entire spectrum in the same period of time as that required... 

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