50, 25, 10 Years Ago

This page offers a look back on a variety of interesting items from Control Engineering's past issues, highlighting content from 50, 25, and 10 years ago. January 1955 Robot Salesmen Book review of: "Automatic Selling," published by John Wiley & Sons. $5.00. Automatic retailing is a big field [$1.

05/01/2004


This page offers a look back on a variety of interesting items from Control Engineering 's past issues, highlighting content from 50, 25, and 10 years ago.

January 1955

Robot Salesmen

Book review of: "Automatic Selling," published by John Wiley & Sons. $5.00. Automatic retailing is a big field [$1.5 billion a year in 1954] with a bigger future so that a book the size of this one can be contented with describing the scope of present operations in the moderately general terms. This book is aimed for a non-engineering audience, but discusses the foundations of the machine vending business in a way that might stimulate those thinking of data processing on a systems level, or process-systems engineers concerned with market variations.

Some interesting observations: customers prefer to push a button to start the delivery cycle, and are confused if the coin alone does the job; one of the headaches facing vending machine manufacturers today is the diversity of cabinet styles and the resultant conglomeration-effect when several are placed together. Some work has been done towards putting a battery of machines behind a single large panel, with only the control and delivery elements protruding. Perhaps a graphic control panel arrangement could conform to dietary lines?

April 1979

Thank Ma Bell for RS-232

There isn't a single-board computer on the market today that doesn't offer an RS-232-C interface, and you'll find it a standard offering on printers, CRTs, cassette drives, and virtually any other low speed peripheral you can lay your hands on. When it was first proposed by the Electronics Industries Association (RS stands for recommended standard and the C for the third version), it was intended as a reliable means of hooking computers to telephone modems. In fact, the Cinch DB-25 type connector, which is synonymous with RS-232, is not even specified in the standard—presumably any 25-pin connector would do—but Bell uses it on its modems and so it stuck.

The standard does define 20 signals, although you might be hard pressed to find a device that uses them all. Curiously, the standard lists 13 specific combinations of signals for use, yet permits any subset. The result is that it is quite possible, and not even uncommon, to interconnect two devices that are compatible with the standard but won't work together. Fortunately, the remedy is usually simple: hardwire the unnecessary signal lines permanently on (or off) and forget about them. The simplest arrangement gets by with only three wires: Signal Ground, Send Data, and Receive Data.

May 1994

Pressure transmitter works with two protocols; control system bridges PC-PLC gap

"Fieldbus First: New Pressure Transmitter 'Speaks' Two Protocols. Smar rolls out the first fieldbus-compatible pressure transmitter, said to work with two different protocols: ISP and WorldFIP. This year, process instrumentation makers hope to deliver on promises they've made to potential fieldbus users. 1994, most of them agree, has to be the year of real stuff. Standing first in line with a sampling of the real stuff is Brazilian-based instrument maker Smar Inc. In fact Smar has not one, but two surprises for the process control world. First, claims Marcos Peluso, applications engineering manager, is a fieldbus- compatible pressure transmitter. The second: with a simple board swap, the new transmitter is compatible with either ISP or WorldFIP protocols...."

"All-In-One Control System Fills the Gap. Beyond the PLC—this medium-sized system has many features of larger process control systems. The design of the user interface is a critical task for the manufacturers of intelligent process control equipment.... The configuration and supervisory features offered with, for example, a PLC and PC are not normally comparable with those of a large process control system. With its new Digimatik system, Hartmann & Braun AG, based in Frankfurt, Germany, claims to have made a significant step towards closing the gap between PLC- or PC-based systems and larger process control systems.... The idea behind the product is to provide the user with hardware similar to a PLC, but to simplify the system configuration with an all-in-one software package running on a PC under Microsoft Windows...."