eBook: Automating Manufacturing Systems; with PLCs


A.13 M

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.
MAP (Manufacturers Automation Protocol) - a network type designed for the factory floor that was widely promoted in the 1980s, but was never widely implemented due to high costs and complexity.
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-to-peer and client/server networks.
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) - can be written to and read from quickly. It requires power to preserve the contents, and is often coupled with a battery or capacitor when long term storage is required. Storage available is over 1MByte
ROM (Read Only Memory) - Programs and data are permanently written on this low cost ship. Storage available is over 1 MByte.
EPROM (ELECTRICALLY Programmable Read Only Memory) - A program can be written to this memory using a special programmer, and erased with ultraviolet light. Storage available over 1MByte. After a program is written, it does not require power for storage. These chips have small windows for ultraviolet light.
EEPROM/E2PROM (Electronically Erasable Programmable Read Only Memory) - These chips can be erased and programmed while in use with a computer, and store memory that is not sensitive to power. These can be slower, more expensive and with lower capacity (measured in Kbytes) than other memories. But, their permanent storage allows system configurations/data to be stored indefinitely after a computer is turned off.
memory map - a listing of the addresses of different locations in a computer memory. Very useful when programming.
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.

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