RS-422/485 Multiport Serial PCI Card
7
3.2.1 JP5: UART Input Clock Speed Selector
3.2.2 JP1: RS-422/485 Mode Selector
Mode Settings for both S1 and S2 (JP1):
Jumper Name
Jumper Positions
Mode and Termination Resistor
Setting
485
(Default)
2-wire RS-485 mode
485/422
422 4-wire
RS-422
mode
RTS
RS-485 Transmitter Buffer Enable is
Controlled by RTS (active high)
RTS/AUTO
AUTO
(Default)
RS-485 Transmitter Buffer is
controlled automatically by ATTA
TM
hardware circuit
422
AUTO
NO_ECHO
NO_LOOP
485
RTS
ECHO
LOOP
HI
LO
W
UART Input Clock Speed = 14.7456MHZ,
the maximum baud rate is 926.1Kbps. In
this setting,
you need go to Windows’
COM port Properties to detect this input
clock automatically and fit this clock
value (see the software setup for more
details)
HI
LOW
UART Input Clock Speed = 1.8432MHZ,
the maximum baud rate is 115.2Kbps
(Default)
RS-422/485 Multiport Serial PCI Card
12
6.
Set RS-485 in 2-wire (Half Duplex)
Mode
To enable your card to work in the RS-485 2-wire mode, please
follow the following steps:
1. Set the Mode Jumpers (JP1) to “485” and “AUTO” as
mentioned in the above sections.
2. Proceed with the following settings in Windows
Right click on
〝
My Computer
〞
and choose
〝
properties
〞
(Win98,ME) or
〝
Manage
〞
(Win2000,XP)
Choose
〝
Device Manager
〞
and double click
〝
Ports
〞
.
You will see the
〝
PCI Communications Port
（
COM3
、
COM4
）
〞
provided by your card.
Double click on
〝
PCI Communications Port (COM3)
〞
or
〝
PCI Communications Port (COM4)
〞
then select
〝
Settings
〞
