Automating Manufacturing Systems - Process Control and ...

plc glossary - 35.12
EPROM (Erasable Programmable Read Only Memory) - a memory type that can be programmed with
voltages, and erased with ultraviolet light.
EPS (Encapsulated PostScript) - a high quality graphics description language understood by high end
printers. Originally developed by Adobe Systems Limited. This standard is becoming very
popular.
error signal - a control signal that is the difference between a desired and actual position.
ESD - see electrostatic discharge.
esters - a chemical that was formed by a reaction between alcohol and an acid.
ETX (End Of Text) - a marker to indicate the end of a text block in data transmission.
even parity - a checksum bit used to verify data in other bits of a byte.
execution - when a computer is under the control of a program, the program is said to be executing.
expansion principle - when heat is applied a liquid will expand.
expert systems - is a branch of artificial intelligence designed to emulate human expertise with software.
Expert systems are in use in many arenas and are beginning to be seen in CAD systems. These
systems use rules derived from human experts.
35.6 F
fail safe - a design concept where system failure will bring the system to an idle or safe state.
false - a logical negative, or zero.
Faraday’s electromagnetic induction law - if a conductor moves through a magnetic field a current will be
induced. The angle between the motion and the magnetic field needs to be 90 deg for maximum
current.
Farenheit - a temperature system that has 180 degrees between the freezing and boiling point of water.
fatal error - an error so significant that a software/hardware cannot continue to operate in a reliable manner.
fault - a small error that may be recoverable, or may result in a fatal error.
FAX (facsimile) - an image is scanned and transmitted over phone lines and reconstructed at the other end.
FCS (Frame Check Sequence) - data check flag for communications.
FDDI (Fibre Distributed Data Interface) - a fibre optic token ring network scheme in which the control
tokens are counter rotating.
FDX (Full Duplex) - all characters that are transmitted are reflected back to the sender.
FEA (Finite Element Analysis) - is a numerical technique in which the analysis of a complex part is
subdivided into the analysis of small simple subdivisions.
feedback - a common engineering term for a system that examines the output of a system and uses is to tune
the system. Common forms are negative feedback to make systems stable, and positive feedback
to make systems unstable (e.g. oscillators).
fetch - when the CPU gets a data value from memory.
fiberoptics - data can be transmitted by switching light on/off, and transmitting the signal through an optical
fiber. This is becoming the method of choice for most long distance data lines because of the low
losses and immunity to EMI.
FIFO (First In First Out) - items are pushed on a stack. The items can then be pulled back off last first.
file - a concept of a serial sequence of bytes that the computer can store information in, normally on the disk.
This is a ubiquitous concept, but file is also used by Allen Bradley to describe an array of data.
filter - a device that will selectively pass matter or energy.
firmware - software stored on ROM (or equivalent).
flag - a single binary bit that indicates that an event has/has not happened.
flag - a single bit variable that is true or not. The concept is that if a flag is set, then some event has
happened, or completed, and the flag should trigger some other event.
flame - an email, or netnews item that is overtly critical of another user, or an opinion. These are common
because of the ad-hoc nature of the networks.
flange - a thick junction for joining two pipes.
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