Kontron PCI-COM-8ULP, Руководство пользователя

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PCI-COM-8ULP User’s Guide page 15
Chapter 1: Introduction
Functional Description
The Serial Interface Card was designed for effective multipoint transmission in any one
of three modes on each channel. These modes are RS232, RS422 and RS485
(EIA485) protocol. The RS485 mode may be run in three manners. It may be run as a
standard RTS controlled channel, an “Auto RTS (referred to by some as Auto RS485)”
mode or as a “4 wire RS485 mode channel.
The card is 6.60 inches long and may be installed in 5-volt PCI-bus slots of IBM PC or
compatible computers. The card features eight independent, asynchronous serial ports,
type 16788 buffered UARTs.
RS422 Balanced Mode Operation
The card supports RS422 communications and uses differential balanced drivers for
long range and noise immunity. The card also has the capability to add load resistors to
terminate the communications lines. RS422 communications requires that a transmitter
supply a bias voltage to ensure a known "zero" state. Also, receiver inputs at each end
of the network should be terminated to eliminate "ringing". The card supports biasing by
default and supports termination by jumpers on the card. If your application requires the
transmitter to be un-biased, please contact the factory.
RS485 Balanced Mode Operation
The card supports RS485 communications and uses differential balanced drivers for
long range and noise immunity. RS485 operation involves switchable transceivers and
the ability to support multiple devices on a single "party line". The RS485 specification
defines a maximum of 32 devices on a single line. The number of devices served on a
single line can be expanded by use of "repeaters".
The card also has the capability to add load resistors to terminate the communications
lines. RS485 communications requires that one transmitter supply a bias voltage to
ensure a known "zero" state when all transmitters are off. Also, receiver inputs at each
end of the network should be terminated to eliminate "ringing". The card supports
biasing by default and supports termination by jumpers on the card. If your application
requires the transmitter to be un-biased, please contact the factory.