Industrial Automation Glossary – J, K, L, M

JIT (Just in Time)
a philosophy when setting up and operating a manufacturing system such that materials required arrive at the work site just in time to be used.

jog
a mode where a motor will be advanced while a button is held, but not latched on. It is often used for clearing jams, and loading new material.

jump
a forced branch in a program

jumper
a short wire, or connector to make a permanent setting of hardware parameters.

k, K
specifies magnitudes. 1K = 1024, 1k = 1000 for computers, otherwise 1K = 1k = 1000. Note

Karnaugh maps
a method of graphically simplifying logic.

Kelvin
temperature units that place 0 degrees at absolute zero. The magnitude of one degree is the same as the Celsius scale.

keying
small tabs, prongs, or fillers are used to stop connectors from mating when they are improperly oriented.

KiloBaud, KBaud, KB, Baud
a transmission rate for serial communications (e.g. RS

kinematics/kinetics
is the measure of motion and forces of an object. This analysis is used to measure the performance of objects under load and/or in motion.

label
a name associated with some point in a program to be used by branch instructions.

ladder diagram
a form of circuit diagram normally used for electrical control systems.

ladder logic
a programming language for PLCs that has been developed to look like relay diagrams from the preceding technology of relay based controls.

laminar flow
all of the particles of a fluid or gas are traveling in parallel. The complement to this is turbulent flow.

LAN (Local Area Network)
a network that is typically less than 1km in distance. Transmission rates tend to be high, and costs tend to be low.

latch
an element that can have a certain input or output lock in. In PLCs these can hold an output on after an initial pulse, such as a stop button.

LCD (Liquid Crystal Display)
a fluid between two sheets of light can be polarized to block light. These are commonly used in low power displays, but they require backlighting.

leakage current
a small amount of current that will be present when a device is off.

LED (Light Emitting Diode)
a semiconductor light that is based on a diode.

LIFO (Last In First Out)
similar to FIFO, but the last item pushed onto the stack is the first pulled off.

limit switch
a mechanical switch actuated by motion in a process.

line printer
an old printer style that prints single lines of text. Most people will be familiar with dot matrix style of line printers.

linear
describes a mathematical characteristic of a system where the differential equations are simple linear equations with coefficients.

little
endian

load
In electrical system a load is an output that draws current and consumes power. In mechanical systems it is a mass, or a device that consumes power, such as a turbine.

load cell
a device for measuring large forces.

logic
1. the ability to make decisions based on given values. 2. digital circuitry.

loop
part of a program that is executed repeatedly, or a cable that connects back to itself.

low
a logic negative, or zero.

LRC (Linear Redundancy Check)
a block check character

LSB (Least Significant Bit)
This is the bit with the smallest value in a binary number. for example if the number 10 is converted to binary the result is 1010. The most significant bit is on the left side, with a value of 8, and the least significant bit is on the right with a value of 1

LSD (Least Significant Digit)
This is the least significant digit in a number, found on the right side of a number when written out. For example, in the number $1,234,567 the digit 7 is the least significant.

LSI (Large Scale Integration)
an integrated circuit that contains thousands of elements.

LVDT (Linear Variable Differential Transformer)
a device that can detect linear displacement of a central sliding core in the transformer.

machine language
CPU instructions in numerical form.

macro
a set of commands grouped for convenience.

magnetic field
a field near flowing electrons that will induce other electrons nearby to flow in the opposite direction.

MAN (Metropolitan Area Network)
a network designed for municipal scale connections.

manifold
1. a connectors that splits the flow of fluid or gas. These are used commonly in hydraulic and pneumatic systems. 2. a description for a geometry that does not have any infinitely small points or lines of contact or separation. Most solid modelers deal only with manifold geometry.

mask
one binary word (or byte, etc) is used to block out, or add in digits to another binary number.

mass flow rate
instead of measuring flow in terms of volume per unit of time we use mass per unit time.

mass spectrometer
an instrument that identifies materials and relative proportions at the atomic level. This is done by observing their deflection as passed through a magnetic field.

master/slave
a control scheme where one computer will control one or more slaves. This scheme is used in interfaces such as GPIB, but is increasingly being replaced with peer

mathematical models
of an object or system predict the performance variable values based upon certain input conditions. Mathematical models are used during analysis and optimization procedures.

matrix
an array of numbers

MB MByte, KB, KByte
a unit of memory commonly used for computers. 1 KiloByte = 1 KByte = 1 KB = 1024 bytes. 1 MegaByte = 1 MByte = 1MB = 1024*1024 bytes.

MCR (Master Control Relay)
a relay that will shut down all power to a system.

memory
binary numbers are often stored in memory for fast recall by computers. Inexpensive memory can be purchased in a wide variety of configurations, and is often directly connected to the CPU.

memory
memory stores binary (0,1) patterns that a computer can read or write as program or data. Various types of memories can only be read, some memories lose their contents when power is off. RAM (Random Access Memory)

menu
a multiple choice method of selecting program options.

message
a short sequence of data passed between processes.

microbar
a pressure unit (1 dyne per sq. cm)

microphone
an audio transducer (sensor) used for sound measurements.

microprocessor
the central control chip in a computer. This chip will execute program instructions to direct the computer.

MILNET (MILitary NETwork)
began as part of ARPANET.

MMI (Man Machine Interface)
a user interface terminal.

mnemonic
a few characters that describe an operation. These allow a user to write programs in an intuitive manner, and have them easily converted to CPU instructions.

MODEM (MOdulator/DEModulator)
a device for bidirectional serial communications over phone lines, etc.

module
a part o a larger system that can be interchanged with others.

monitor
an operation mode where the computer can be watched in detail from step to step. This can also refer to a computer screen.

motion detect flow meter
a fluid flow induces measurement.

MRP (Material Requirements Planning)
a method for matching material required by jobs, to the equipment available in the factory.

MSD (Most Significant Digit)
the largest valued digit in a number (eg. 6 is the MSD in 63422). This is often used for binary numbers.

MTBF (Mean Time Between Failure)
the average time (hours usually) between the last repair of a product, and the next expected failure.

MTTR (Mean Time To Repair)
The average time that a device will out of use after failure before it is repaired. This is related to the MTBF.

multicast
a broadcast to some, but not necessarily all, hosts on a network.

multiplexing
a way to efficiently use transmission media by having many signals run through one conductor, or one signal split to run through multiple conductors and rejoined at the receiving end.

multiprocessor
a computer or system that uses more than one computer. Normally this term means a single computer with more than one CPU. This scheme can be used to increase processing speed, or increase reliability.

multivibrator
a digital oscillator producing square or rectangular waveforms.