Impulse 7106 - Manual (Page 14)

© Sealevel Systems, Inc. - 12 - 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.