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Chapter 3
Table 3-14. Serial A Interface Pin/Signal Descriptions (J11)
Pin # Pin #
DB9
1
1
(COM1)
2
6
3
2
4
7
5
3
6
8
7
4
8
9
9
5
10
NC
11
1
(COM2)
12
6
13
2
14
7
15
3
42
Signal
Description
DCD1* Data Carrier Detect 1 – Indicates external serial communications device
is detecting a carrier signal (i.e., a communication channel is currently
open). In direct connect environments, this input will be driven by DTR1
as part of the DTR/DSR handshake.
DSR1*
Data Set Ready 1 – Indicates external serial communications device is
powered, initialized, and ready. Used as hardware handshake with DTR1
for overall readiness to communicate.
RXD1
Receive Data 1 – Serial port 1 receive data in.
RX1-
RX1- – If in RS485 or RS422 mode, this pin is Receive Data 1 -.
RTS1*
Request To Send 1 – Indicates Serial port 1 is ready to transmit data.
Used as hardware handshake with CTS1 for low level flow control.
TX1+
TX1+ – If in RS485 or RS422 mode, this pin is Transmit Data 1 +.
TXD1
Transmit Data 1 – Serial port 1 transmit data out.
TX1-
TX1- – If in RS485 or RS422 mode, this pin is Transmit Data 1 -.
CTS1*
Clear to Send 1 – Indicates external serial communications device is
ready to receive data. Used as hardware handshake with RTS1 for low
level flow control.
RX1+
RX1+ – If in RS485 or RS422 mode, this pin is Receive Data 1 -.
DTR1* Data Terminal Ready 1 – Indicates this Serial port is powered, initialized,
and ready. Used as hardware handshake with DSR1 for overall readiness
to communicate.
RI1*
Ring Indicator 1 – Indicates external serial communications device is
detecting a ring condition. Used by software to initiate operations to
answer and open the communications channel.
GND
Ground
KEY/
Key
NC
Not connected
DCD2* Data Carrier Detect 2 – Indicates external serial communications device
is detecting a carrier signal (i.e., a communication channel is currently
open). In direct connect environments, this input will be driven by DTR2
as part of the DTR/DSR handshake.
DSR2*
Data Set Ready 2 – Indicates external serial communications device is
powered, initialized, and ready. Used as hardware handshake with DTR2
for overall readiness to communicate.
RXD2
Receive Data 2 – Serial port 2 receive data in
RX2-
RX1- – If in RS485 or RS422 mode, this pin is Receive Data 1 -.
RTS2*
Request To Send 2 – Indicates Serial port 2 is ready to transmit data.
Used as hardware handshake with CTS2 for low level flow control.
TX2+
TX2+ – If in RS485 or RS422 mode, this pin is Transmit Data 2 +.
TXD2
Transmit Data 2 – Serial port 2 transmit data out
TX2-
TX2- – If in RS485 or RS422 mode, this pin is Transmit Data 2 -.
Reference Manual
Hardware
LittleBoard 800
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