B&R Industries Automation PC 620, User Manual

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Appendix A • Glossary
Automation PC 620 User's Manual V 1.90
Interface
From the hardware point of view, an interface is the connection point between two
modules/devices/systems. The units on both sides of the interface are connected by the
interface lines so that data, addresses and control signals can be exchanged. The term interface
includes all functional, electrical and constructive conditions [coding, signal level, pin
assignments], which characterize the connection point between the modules, devices or
systems. Depending on the type of data transfer, a differentiation is made between parallel [e.g.
Centronics, IEEE 488] and serial interfaces [e.g. V.24, TTY, RS232, RS422, RS485], which are
set up for different transfer speeds and transfer distances. From the point of view of software,
the term interface describes the transfer point between program modules using specified rules
for transferring the program data.
ISA
An abbreviation for »Industry Standard Architecture« A term given for the bus design which
allows expansion of the system with plug-in cards which can be inserted in the expansion slots
provided in the PC.
ISO
International Organization for Standardization > Worldwide federation of national
standardization institutions from over 130 countries. ISO is not an acronym for the name of the
organization; it is derived from the Greek word isos, meaning "equal" (www.iso.ch).
Jitter
Jitter is a term that describes time deviations of cyclic events. If, for example, an event should
take place every 200s and it actually occurs every 198 to 203s, then the jitter is 5s. Jitter has
many causes. It originates in the components and transfer media of networks because of noise,
crosstalk, electromagnetic interference and many other random occurrences. In automation
technology, jitter is a measure of the quality of synchronization and timing.
Jumper
A small plug or wire link for adapting the hardware configuration. Used to connect the different
points of an electronic circuit.
LCD
An abbreviation for »Liquid Crystal Display« A display type, based on liquid crystals which have
a polarized molecular structure and are enclosed between two transparent electrodes as a thin
layer. If an electrical field is applied to the electrodes, the molecules align themselves with the
field and form crystalline arrangements, which polarize the light passing through. A polarization
filter, which is arranged using lamellar electrodes, blocks the polarized light. In this way, a cell
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