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tem, or something to "connect instru ment to computer," presupposes that you have fully identified the solution to the problem you are trying to solve. You also bias the vendor's response in a particular direction, which may not have anything to do with the real prob lem. By presenting vendors with your problem rather than your perceived need, you may discover possibilities that previously had not occurred to you. Communications
Looks at current progress and understanding from the point of view of solid-state chemistry . . . Hot off the presses! This new book presents the most current informa tion in developing technologies for commercial uses of high-temperature superconductivity. Although this area is multidisdplinary, chemistry plays a key role throughout. . . from materials preparation to processing for small- and large-scale operations. This book presents the chemistry nec essary to further the research in this exciting area.
Information is presented in the following major areas: • Theory · Materials Preparation and Characterization · Structure-Prop erty Relationships · Surfaces and Interfaces · Processing and Fabrication • Applications · Research Needs and Opportunities
The editors are . . . • David L. Nelson, Office of Naval Research · M. Stanley Whittingham, Schlumberger-Doll Research · Thomas F. George, State University of New York at Buffalo
Plus more than 100 contributors from major research groups worldwide! \C J ">,",'•
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98 A · ANALYTICAL CHEMISTRY, VOL. 60, NO. 2, JANUARY 15, 1988
Communications are essential for the proper implementation of a laboratory automation project. Of all the funda mental technical requirements, com munications suffer the most from a lack of standardization. Basically, the system requires communication both from the instrument to the data system and between data systems. Generally the producers of instru mentation for chemical analysis and data stations have adopted the RS232 serial ASCII port as a common means of transmitting data to computer sys tems. When you ask if a particular in strument or data system can be con nected to a larger computer system, the typical response is "Sure, we have an RS232 connection." But have they really told you anything? RS232 refers to a recommended standard (the RS part) for the trans mission of characters (each having a unique 7- or 8-bit code that indicates which character is being sent) between two devices such as a computer and a terminal or printer. The recommended standard specifies the functions of wir ing connections that are used to make the physical connection and the voltage levels that are used to designate the logical " 0 " and " 1 " that represent char acter code. If the recommended standard is fol lowed, you can be reasonably assured that a character sent from one device will be received by a second device, that is, unless an error occurs on the way. Error handling is the beginning of the problem, and it is not addressed by the RS232 specification. Let us look at the problem we are really trying to solve. We have two de vices. Assume that one is an instrument system with a microprocessor in it that will take the digitized values from the experiment, analyze them, and cause them and the results to be sent to a computer via the RS232 port. The sec ond device is the computer system, which can be programmed to accept the data. The data and the result need to be transmitted. Together they con stitute a message t h a t i n turn is made up of individual characters. If the mes sage is to be sent and received correct ly, several things must happen. First, we have to understand the for-
