Automating Manufacturing Systems - Process Control and ...

plc glossary - 35.10
geometric dimensions, material type, tolerances, and engineering notes.
detector - a device to determine when a certain condition has been met.
device driver - controls a hardware device with a piece of modular software.
DFA (Design For Assembly) - a method that guides product design/redesign to ease assembly times and
difficulties.
DFT (Design for Testability) - a set of design axioms that generally calls for the reduction of test steps, with
the greatest coverage for failure modes in each test step.
diagnostic - a system or set of procedures that may be followed to identify where systems may have failed.
These are most often done for mission critical systems, or industrial machines where the user may
not have the technical capability to evaluate the system.
diaphragm - used to separate two materials, while allowing pressure to be transmitted.
differential - refers to a relative difference between two values. Also used to describe a calculus derivative
operator.
differential amplifier - an amplifier that will subtract two or more input voltages.
diffuse field - multiple reflections result in a uniform and high sound pressure level.
digital - a system based on binary on-off values.
DIN (the Deutsches Institut for Normung) - a German standards institute.
diode - a semiconductor device that will allow current to flow in one direction.
DIP switches - small banks of switches designed to have the same footprint as an integrated circuit.
distributed - suggests that computer programs are split into parts or functions and run on different computers
distributed system - a system can be split into parts. Typical components split are mechanical, computer,
sensors, software, etc.
DLE (Data Link Escape) - An RS-232 communications interface line.
DMA (Direct Memory Access) - used as a method of transferring memory in and out of a computer without
slowing down the CPU.
DNS (Domain Name System) - an internet method for name and address tracking.
documentation - (don’t buy equipment without it) - one or more documents that instruct in the use,
installation, setup, maintenance, troubleshooting, etc. for software or machinery. A poor design
supported by good documentation can often be more useful than a good design unsupported by
poor documentation.
domain - the basic name for a small or large network. For example (unc.edu) is the general extension for the
University on North Carolina.
doppler shift - as objects move relative to each other, a frequency generated by one will be perceived at
another frequency by the other.
DOS (Disk Operating System) - the portion of an operating system that handles basic I/O operations. The
most common example is Microsoft MS-DOS for IBM PCs.
dotted decimal notation - the method for addressing computers on the internet with IP numbers such as
‘129.100.100.13’.
double pole - a double pole switch will allow connection between two contacts. These are useful when
making motor reversers. see also single pole.
double precision - a real number is represented with 8 bytes (single precision is 4) to give more precision for
calculations.
double throw - a switch or relay that has two sets of contacts.
download - to retrieve a program from a server or higher level computer.
downtime - a system is removed from production for a given amount of downtime.
drag - a force that is the result of a motion of an object in a viscous fluid.
drop - a term describing a short connection to peripheral I/O.
drum sequencer - a drum has raised/lowered sections and as it rotates it opens/closes contacts and will give
sequential operation.
dry contact - an isolated output, often a relay switched output.
DSP (Digital Signal Processor) - a medium complexity microcontroller that has a build in floating point unit.
These are very common in devices such as modems.
DSR (Data Set Ready) - used as a data handshake in asynchronous communications.
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