Automating Manufacturing Systems - Process Control and ...

plc glossary - 35.26
shield - a grounded conducting barrier that steps the propagation of electromagnetic waves.
Siemens - a measure of electrical conductivity.
signal conditioning - to prepare an input signal for use in a device through filtering, amplification,
integration, differentiation, etc.
simplex - single direction communication at any one time.
simulation - a model of the product/process/etc is used to estimate the performance. This step comes before
the more costly implementation steps that must follow.
single-discipline team - a team assembled for a single purpose.
single pole - a switch or relay that can only be opened or closed. See also single pole.
single throw - a switch that will only switch one line. This is the simplest configuration.
sinking - using a device that when active will allow current to flow through it to ground. This is
complimented by sourcing.
SLIP (Serial Line internet Protocol) - a method to run the internet Protocol (IP) over serial lines, such as
modem connections.
slip-ring - a connector that allows indefinite rotations, but maintains electrical contacts for passing power
and electrical signals.
slurry - a liquid with suspended particles.
SMTP (Simple Mail Transfer Protocol) - the basic connection protocol for passing mail on the internet.
snubber - a circuit that suppresses a sudden spike in voltage or current so that it will not damage other
devices.
software - a program, often stored on non-permanent media.
solenoid - an actuator that uses a magnetic coil, and a lump of ferrous material. When the coil is energized a
linear motion will occur.
solid state - circuitry constructed entirely of semiconductors, and passive devices. (i.e., no gas as in tubes)
sonar - sound waves are emitted and travel through gas/liquid. they are reflected by solid objects, and then
detects back at the source. The travel time determines the distance to the object.
sound - vibrations in the air travel as waves. As these waves strike the human ear, or other surfaces, the
compression, and rarefaction of the air induces vibrations. In humans these vibrations induce
perceived sound, in mechanical devices they manifest as distributed forces.
sound absorption - as sound energy travels through, or reflects off a surface it must induce motion of the
propagating medium. This induced motion will result in losses, largely heat, that will reduce the
amplitude of the sound.
sound analyzer - measurements can be made by setting the instrument for a certain bandwidth, and centre
frequency. The measurement then encompasses the values over that range.
sound level - a legally useful measure of sound, weighted for the human ear. Use dBA, dBB, dBC values.
sound level meter - an instrument for measuring sound exposure values.
source - an element in a system that supplies energy.
sourcing - an output that when active will allow current to flow from a voltage source out to a device. It is
complimented by sinking.
specific gravity - the ratio between the density of a liquid/solid and water or a gas and air.
spectrometer - determines the index of refraction of materials.
spectrophotometer - measures the intensities of light at different points in the spectrum.
spectrum - any periodic (and random) signal can be described as a collection of frequencies using a
spectrum. The spectrum uses signal power, or intensity, plotted against frequency.
spherical wave - a wave travels outward as if on the surface of an expanding sphere, starting from a point
source.
SQL (Structured Query Language) - a standard language for interrogating relational databases.
standing wave - if a wave travels from a source, and is reflected back such that it arrives back at the source
in phase, it can undergo superposition, and effectively amplify the sound from the source.
static head - the hydrostatic pressure at the bottom of a water tank.
steady state - describes a system response after a long period of time. In other words the transient effects
have had time to dissipate.
STEP (Standard for the Exchange of Product model data) - a standard that will allow transfer of solid model
data (as well as others) between dissimilar CAD systems.