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Staff -- Control Engineering, 3/1/2004

October 1954

Prospects Are Bright For Smell That's Right

How can you apply feedback control to something you can't measure? You can't. That's what disturbs engineers in the food industry, who want to regulate flavor and odor automatically.

Odor measurement has finally reached the distinct-possibility stage, judging from a paper presented as this issue went to press at the American Chemical Society's national meeting in New York. Robert W. Moncrieff, a consultant from Girvan, Scotland, reported experiments on the adsorption of odorants.

According to one theory, your smell sensation depends on the way nerve terminals in your nose absorb tiny amounts of vapor. Dr. Moncrieff confesses: "It is not practicable to use those adsorbents which occur in the olfactory area." But in working with such common adsorbents as carbon and silica gel, he has found that odor quality and adsorption characteristics correlate closely. Thus some sort of adsorption meter could conceivably be the sensing element for automatic odor control.

The day may come when restaurants advertise "Automatic Cuisine" or a perfume manufacturer can set a potentiometer to "Chanel No. 5."

DEC's PDP-11/34 Mini has been Squeezed into a Single Board Micro

The components group of the Digital Equipment Corporation has just announced the introduction of the LSI-11/23 single board microcomputer, another piece of evidence that the distinction between minicomputers and microcomputers is vanishing into silicon. Utilizing MOS/LSI technology, DEC has developed a 16-bit, high-performance microprocessor in a single, dual-height, multi-layer module. It has brought full PDP-11/34 functionality to a processor that communicates along the LSI-11 bus. Memory is available from a modest 8K bytes to a startling capacity of 256K bytes. For units with memory above 64K bytes, PDP-11/34 memory management and protection is standard, and a single (32-bit) or double (64-bit) floating point is available as an option.

The LSI-11/23 is software compatible with the full range of PDP-11/34 software and is capable of running sophisticated, real-time, multi-tasking software both in the development and run-time environments. Programs are executed some 250% faster than either the LSI-11 or the LSI-11/2 and 90% as fast as the PDP-11/34 without cache or floating point.

PLC Users Get New Packing Options

"The traditional rack-mounted PLC is beginning to look old fashioned! The micro has become the darling of the PLC industry, and while it may not be a big money maker, none will deny its volume is soaring. PLC manufacturers used to consider it as merely a relay replacer, a little plastic brick ... to fill out their product lines. No more. Micros are getting respect," wrote then editor-in-chief Michael Babb.

He discussed how direct sales, via telephone, with a credit card was starting to take hold, the start of modular construction without a backplane, and the beginning of the end for the "brick PLC."

Discussions included the Square D PCX with an Intel "386-based PC card"; Siemens anticipated blending of its S5 PLC with the acquired Texas Instruments PLC line; Omron's Sysmac CQM1, designed to eliminate wasted I/O; Mitsubishi's FX2C line (half the footprint of previous units); and Allen-Bradley's 1794 "Flex I/O."

"During the middle to late 1970s, remote I/O came into being. It was the first department from locating all the I/O in the same cabinet with the CPU....The strategy provided major cost saving to PLC users because wiring between I/O modules and the field devices could be run over much shorter distances," said Babb.

"OEMs and end-users want a range of interoperable solutions for their applications. The evolution of I/O has ultimately been the story of greater flexibility, lower cost and higher competitiveness for end-users and OEMs alike. With the introductions this spring, it can be said that PLC makers are giving the panel builders more of what they need to build cost-effective control systems." Such options promised to cut panel costs by 10-20%.