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© Sealevel Systems, Inc. 7406e Manual | SL9252 10/2022
Technical Description
The COMM+4/232.PCIe provides four RS-232 ports from a single PCIe slot.
The COMM+4/232.PCIe utilizes the OXPCIe954 type UART. This chip features programmable baud rates,
data format, interrupt control and industry leading 128-byte transmit and receive FIFOs.
The UARTs are register compatible with 16C450, 16C550, 16C654 and 16C750 UARTs. The FIFO depth can
be changed to match the depth of these UARTs.
RS-232 (CA-199 DB-25) Connector Pin Assignments
Signal
Name
Pin #
Mode
GND
Ground
7
TD
Transmit Data
2
Output
RTS
Request To Send
4
Output
DTR
Data Terminal Ready
20
Output
RD
Receive Data
3
Input
CTS
Clear To Send
5
Input
DSR
Data Set Ready
6
Input
DCD
Data Carrier Detect
8
Input
RI
Ring Indicator
22
Input
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 ensure you get the best performance from your adapter.
