PLC


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PLC

PLC

(1) (Power Line Communications) See broadband over power lines.

(2) (Programmable Logic Controller) A programmable microprocessor-based device that is used in discrete manufacturing to control assembly lines and machinery on the shop floor as well as many other types of mechanical, electrical and electronic equipment in a plant. Typically RISC based and programmed in an IEC 61131 programming language, a PLC is designed for real-time use in rugged, industrial environments. Connected to sensors and actuators, PLCs are categorized by the number and type of I/O ports they provide and by their I/O scan rate.

In the late 1960s, PLCs were first used to replace the hardwired networks of relays and timers in automobile assembly lines, which were partially automated at that time. The programmability of the PLC enabled changes to be effected considerably faster. Contrast with PAC and DCS. See IEC 61131.
References in periodicals archive ?
Features: Electric heating, PLC controls, closed-loop pressure control.
Features: Electric heat, PLC controls, closed-loop pressure control.
However, they satisfy a completely different niche on the factory floor than the PLC on a Chip, which can be embedded into sensors, motor drives, machine and engine controls, remote control and monitoring system (such as SCADA systems)--you name it.
To satisfy both camps, most of the conventional PLC vendors provide soft PLCs.
However, adds Nesi, "we also like to position it as a good deal more than just a PLC.
Founded in 1985, PLC Systems is headquartered in Milford, Mass.
NOTE: The Heart Laser is a registered trademark of PLC Systems Inc.
Ninety percent of the applications out there are still served by a central PLC, but we do see a growing demand for distributed control on complex jobs," says marketing manager Mark Wedel.
In contrast to hardwired central systems, where individual wires run from each loading station back to the main PLC, distributed systems typically have a single cable connecting all the loading stations in a "daisy-chain" arrangement.
07:00 DGE Diageo PLC Preliminary results, year ended 30
06/10/2008 13:37 DGE Diageo PLC Transaction in Own Shares
02/10/2006 17:05 DGE Diageo PLC Transaction in Own Shares