Chapter 2 Installation and Verification
©
National Instruments Corporation
2-11
Serial for Windows NT
Table 2-3. DB-25 Pin Descriptions
DB-25 Pin
AT-232 Signal
AT-485 Signal
Pin 2
TXD
RTS+ (HSO+)
Pin 3
RXD
CTS+ (HSI+)
Pin 4
RTS
RTS- (HSO-)
Pin 5
CTS
TXD+
Pin 6
DSR*
CTS- (HSI-)
Pin 7
GND
RXD-
Pin 8
DCD*
GND
Pin 20
DTR*
RXD+
Pin 22
RI*
TXD-
Pins not listed in this table are No Connect.
*
These signals are not supported by the isolated 232 ports.
Figure 2-8 shows how to connect the cables when you install a four-port
version of the AT serial board.
AT Serial Board
Additional
Serial Cable
Additional
Serial Cable
10-position modular jack
to DB-9 cable
10-position modular jack
to DB-25 cable
485 Terminator
(AT-485 only)
Figure 2-8. Connecting the Cables to Your Four-Port AT Serial Board
