Automating Manufacturing Systems - Process Control and ...

plc glossary - 35.15
function.
impedance - In electrical systems this is both reactive and real resistance combined. This also applies to
power transmission and flows in other types of systems.
impulse Noise - a short duration, high intensity noise. This type of noise is often associated with explosions.
increment - increase a numeric value.
inductance - current flowing through a coil will store energy in a magnetic field.
inductive heating - a metal part is placed inside a coil. A high frequency AC signal is passed through the coil
and the resulting magnetic field melts the metal.
infrared - light that has a frequency below the visible spectrum.
inertia - a property where stored energy will keep something in motion unless there is energy added or
released.
inference - to make a decision using indirect logic. For example if you are wearing shoes, we can infer that
you had to put them on. Deduction is the complementary concept.
inference engine - the part of an expert system that processes rules and facts using forward or backward
chaining.
Insertion Loss - barriers, hoods, enclosures, etc. can be placed between a sound source, and listener, their
presence increases reverberant sound levels and decreases direct sound energy. The increase in
the reverberant sound is the insertion loss.
instruction set - a list of all of the commands that available in a programmable system. This could be a list of
PLC programming mnemonics, or a list of all of the commands in BASIC.
instrument - a device that will read values from external sensors or probes, and might make control decision.
intake stroke - in a piston cylinder arrangement this is the cycle where gas or liquid is drawn into the
cylinder.
integral control - a control method that looks at the system error over a long period of time. These controllers
are relatively immune to noise and reduce the steady state error, but the do not respond quickly.
integrate - to combine two components with clearly separable functions to obtain a new single component
capable of more complex functions.
intelligence - systems will often be able to do simple reasoning or adapt. This can mimic some aspects of
human intelligence. These techiques are known as artificial intelligence.
intelligent device - a device that contains some ability to control itself. This reduces the number of tasks that
a main computer must perform. This is a form of distributed system.
interface - a connection between a computer and another electrical device, or the real world.
interlock - a device that will inhibit system operation until certain cnditions are met. These are often required
for safety on industrial equipment to protect workers.
intermittent noise - when sounds change level fluctuate significantly over a measurement time period.
internet - an ad-hoc collection of networks that has evolved over a number of years to now include millions
of computers in every continent, and by now every country. This network will continue to be the
defacto standard for personal users. (commentary: The information revolution has begun already,
and the internet has played a role previously unheard of by overcoming censorship and
misinformation, such as that of Intel about the Pentium bug, a military coup in Russia failed
because they were not able to cut off the flow of information via the internet, the Tianneman
square massacre and related events were widely reported via internet, etc. The last stage to a
popular acceptance of the internet will be the World Wide Web accessed via Mosiac/Netscape.)
internet address - the unique identifier assigned to each machine on the internet. The address is a 32 bit
binary identifier commonly described with the dotted decimal notation.
interlacing - is a technique for saving memory and time in displaying a raster image. Each pass alternately
displays the odd and then the even raster lines. In order to save memory, the odd and even lines
may also contain the same information.
interlock - a flag that ensures that concurrent streams of execution do not conflict, or that they cooperate.
interpreter - programs that are not converted to machine language, but slowly examined one instruction at a
time as they are executed.
interrupt - a computer mechanism for temporarily stopping a program, and running another.
inverter - a logic gate that will reverse logic levels from TRUE to/from FALSE.
I/O (Input/Output) - a term describing anything that goes into or out of a computer.
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