COMHP 7404/-D25
CyberResearch
®
Serial Communications
8
©Copyright 2010
CyberResearch, Inc.
Technical Description
The CyberResearch
®
COMHP 7404
provides a PCI interface adapter with 4 RS-232/422/485 asynchronous serial ports for
industrial automation and control applications.
The
COMHP 7404
utilizes the 16C864 UART. This chip features programmable baud rates, data format, interrupt control
and industry leading 128-byte transmit and receive FIFOs.
Connector Pin Assignments
RS-422/485 (DB 9 Male)
Signal Name Pin
#
Mode
GND Ground
5
TX +
Transmit Data Positive
4
Output
TX-
Transmit Data Negative
3
Output
RTS+
Request To Send Positive
6
Output
RTS-
Request To Send Negative
7
Output
RX+
Receive Data Positive
1
Input
RX-
Receive Data Negative
2
Input
CTS+
Clear To Send Positive
9
Input
CTS-
Clear To Send Negative
8
Input
RS-232 (DB-9
Male)
Signal Name
Pin
# Mode
GND Ground
5
TD Transmit
Data
3
Output
RTS
Request To Send
7
Output
DTR
Data Terminal Ready
4
Output
RD Receive
Data
2 Input
CTS
Clear To Send
8
Input
DSR
Data Set Ready
6
Input
DCD
Data Carrier Detect
1
Input
RI Ring
Indicator
9
Input
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 ensure you
get the best performance from your adapter.
