Technical Description
Sealevel Systems
ULTRA
COMM+I.LPCI
Page
8
Technical Description
The Sealevel Systems
ULTRA COMM+I.LPCI
provides a PCI interface adapter with an isolated asynchronous
serial port providing a versatile interface, field selectable as RS-232 for modems, printers and plotters, as well as
RS-422/485 for industrial automation and control applications. Isolation is important in installations where the
equipment being connected to the PC is either far from the PC, or on a different power transformer circuit. Ground
loop current is a commonly neglected and misunderstood phenomenon that leads to data loss and the destruction of
communications interfaces.
The
ULTRA COMM+I.LPCI
utilizes the 16C850 UART. This chip features programmable baud rates, data
format, interrupt control and industry leading 128-byte FIFOs.
Connector Pin Assignments
RS-232 Signals (DB-25 Male)
Signal Name Pin
#
Mode
GND Ground
7
RD Receive
Data
3 Input
CTS
Clear To Send
5
Input
TD
Transmit Data
2
Output
RTS
Request to Send
4
Output
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. Terminating these pins, if not used, will help insure you get the best performance from your
adapter.
RS-422/485/530 Pin Assignments (DB-25 Male)
Signal
Name
Pin
# Mode
GND
Ground
7
RDB
RX+
Receive Data Positive
16
Input
RDA
RX-
Receive Data Negative
3
Input
CTSB
CTS+
Clear To Send Positive
13
Input
CTSA
CTS-
Clear To Send Negative
5
Input
TDB
TX+
Transmit Data Positive
14
Output
TDA
TX-
Transmit Data Negative
2
Output
RTSB
RTS+
Request To Send Positive
19
Output
RTSA
RTS-
Request To Send Negative
4
Output