Serial / Parallel/ V.35 Cables
Serial data transmission is the most common method of transmitting data from one work station to another. Information is broadcast from one source to another, one bit at a time, over one channel. Computers assimilate
data by passing it through a serial interface; thereby trans- forming it into usable serial data. Then it passes through various ports, cables, and connectors that link the various devices.
There are three types of RS-232C connections; electrical, functional, and mechanical. The most
commonly used is the D-shell, 25 pin or DB25 which normally connects work stations, etc. to peripherals like modems, converters, etc. There are two leads involved; a transmit and receive lead.
RS-449 normally refers to synchronous transmissions employing binary data transmission modes. It identifies signals that correspond to certain pin number assignments for use with DB37 and DB9 connectors.
RS-530 supercedes RS-449 and supports RS-232. Based on the 25-pin connection, it operates with both RS-422 or RS-423. It further defines the variety of mechanical/electrical interfaces between
computers/ workstations that transmit binary serial data (synchronous or asynchro- nous). RS-530 provides the means to obtain higher data rates when used with the standard RS-232 connector.
RS-422 defines any balanced interface without any physical intercon- nection. This standard refers to any of the wide variety of connectors employed such as DB9, DB25 with non-standard pinning; DB25 fol-
lowing RS-530, and DB37 following RS-449. RS-422 is commonly used in point-to-point communications. Binary signals can run at high speeds over long distances.
RS-485 is similar to RS-422 except that transmissions are three way instead of two way. Commonly used in applications where one work station controls multiple peripherals. Up to 64 devices may be con-
nected using this method.
V.35 assemblies are used primarily in high speed modem applica- tions. The V.35 cable assembly is a
shielded 34 conductor inter- face and is available in plenum and non-plenum versions. Custom lengths and special wiring configurations as well as hybrid style assemblies are also available.