Newsgroups: comp.robotics
Subject: WHAT ARE PLCS?
From: anthony.tekatch@canrem.com (Anthony Tekatch)
Path: brunix!sgiblab!darwin.sura.net!howland.reston.ans.net!cs.utexas.edu!utnut!torn!uunet.ca!uunet.ca!portnoy!canrem.com!anthony.tekatch
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Date: Thu, 14 Apr 94 09:33:00 -0400
Organization: CRS Online  (Toronto, Ontario)
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MAC>A friend would like to know what a PLC is.  He says it has something
MAC>to do with controls, and might stand for something like programmable
MAC>logic controllers.  Also, what programming language is used to program
MAC>a PLC?

Your friend is right, PLC does stand for Programmable Logic Controller. The
language is like the language used when programming your VCR. It's a high level
language that is specific to that controller. Basically most controllers deal
with the programs as if they are a relay ladder logic diagram. These controllers
are much more expensive than a micro, but the PLC has all the hardware built in
(like relays and buffered inputs). The response time of the circuit is usually
much slower than a dedicated micro since the PLC must cycle through all inputs
before activating certain outputs.

Anthony
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