User manual

ULTRA 530.LPCI User Manual

Technical Description

The Sealevel Systems ULTRA 530.LPCI provides a PCI interface adapter with an

additional asynchronous serial port providing a versatile interface, field selectable as

RS-232 for modems, printers and plotters, as well as RS-422/485/530 for industrial

automation and control applications.

The ULTRA 530.LPCI utilizes the 16850 UART. This chip features programmable

baud rates, data format, interrupt control and a 128-byte input and output FIFO. The

ULTRA 530.LPCI also supports the Oxford Semiconductor 16C950. This chip

features the same FIFO, and automatic RS-485 driver enable capabilities as the

16C850 and the ability to receive a clock for isochronous communications.

Isochronous Communications

Webster's New Collegiate Dictionary defines synchronous as "recurring or operating

at exactly the same period." The majority of the serial buses in use today operate

asynchronously, that is, "not synchronous" or more literally, not clocked. The same

dictionary defines isochronous as "uniform in time; having equal duration; and

recurring at regular intervals." In this implementation of serial communications,

isochronous is defined as asynchronous framing (i.e. start, stop and parity bits) with

the addition of a clock signal. This scheme allows for much higher data rates and the

use of digital lines (i.e. ISDN, T1) where a clock is supplied for data multiplexing.

Connector Pin Assignments

RS-232 Signals (DB25 Male)

Signal Name Pin # Mode

GND Ground 7

RD Receive Data 3 Input

CTS Clear To Send 5 Input

DSR Data Set Ready 6 Input

TXC Transmit Clock 15 Input

RXC Receive Clock 17 Input

DCD Data Carrier. Detect 8 Input

RI Ring Indicator 22 Input

TD Transmit Data 2 Output

RTS Request to Send 4 Output

TSET Transmit Signal Element Timing 24 Output

DTR Data Terminal Ready 20 Output

Note: These assignments meet EIA/TIA/ANSI-232E DTE

Technical Note: Please terminate any control signals that are not going to be used.

The most common way to do this is connect RTS to CTS and RI. Also, connect

DCD to DTR and DSR. Terminating these pins, if not used, will help insure you get

the best performance from your adapter.