User`s manual

Technical Description
The COMHP 7804 provides eight RS-232/422/485 ports from a single PCI slot. The COMHP 7804
also features Universal Bus (3.3 and 5.0V) operation.
The COMHP 7804 utilizes the 16C864 UART. This chip features programmable baud rates, data format,
interrupt control and industry leading 128-byte transmit and receive FIFOs.
RS-422/485 (DB-9) Connector Pin Assignments
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) Connector Pin Assignments
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.
RS-232/422/485 (DB-78)
Port # 1 2 3 4 5 6 7 8
RS-422/485 RS-232
TX- TD 36 12 27 3 75 51 66 42
RX- RD 37 11 28 2 76 50 67 41
RTS- RTS 17 31 8 22 56 70 47 61
CTS- CTS 16 32 7 23 55 71 46 62
TX+ DTR 35 13 26 4 74 52 65 43
RTS+ DSR 18 30 9 21 57 69 48 60
RX+ DCD 38 10 29 1 77 49 68 40
CTS+ RI 15 33 6 24 54 72 45 63
GND GND 34 14 25 5 73 53 64 44
CyberResearch
®
Serial Communications COMHP 7804
CyberResearch, Inc. 6
25 Business Park Drive P: [phone]; F: [phone]
Branford, CT USA
www.cyberresearch.com