Specifications

Appendix C - Glossary of Terms RS-422 And RS-485 Applications Ebook
Page 101 of 137 Manual Documentation Number: <DocNumber>
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Bar Code Readers / Scanners
Devices used to read bar codes into a computer. Used at Point-of-Sale (POS)
checkout counters, for pricing, inventory control, parts tracking, routing or
shipping documents.
Baud Rate
In most cases baud rate equals the number of bits per second. However, baud
refers to the time period during which one representation of data occurs. In
some cases--for example, in modems that use modulation techniques--several
bits can be represented during one time period. This makes it possible for the
bit rate to be a multiple of the baud rate. For example, if a modem operating
at 9600 baud represents four bits of data using quadrature amplitude
modulation (QAM), the bit rate can be communicating at a rate of 38,400 bits
per second.
Bus
Electrical interconnections in common with other circuits or devices. A power
bus provides a common source of power connections, a ground bus, common
ground connections for power and/or signal common. A RS-485 bus is the
network of wiring joining various RS-485 devices together.
A computer bus provides for internal expansion cards, one of the first
commonly used busses was the S-100 bus used on CPM machines. The original
IBM personal computer has an 8-bit data bus, the original AT has a 16-bit data
bus. These were copied for compatibility with other computers. The PC bus and
PC-AT bus interface is now called ISA for Industry Standard Architecture. There
are other common busses, including PCI and a variety of industrial busses.
To expand a PCs serial ports or add other functions using a internal card, the
type of expansion bus must be known. Check the specifications, verify that the
desired bus slot is unused. PCI bus or ISA slots are common in desktops,
PCMCIA slots on laptops, USB (Universal Serial Bus) connectors may be
available for external expansion on desktops or laptops.