Ampro Corporation Single Board Computer Littleboard 550 User Manual
Page 51
Chapter 3
Hardware
LittleBoard 550
Reference Manual
45
Pin #
Pin #
DB9
Signal
Description
16
8
CTS2*
RX2+
Clear To Send 2 – Indicates external serial communications device is
ready to receive data. Used as hardware handshake with RTS2 for low
level flow control.
RX2+ – If in RS485 or RS422 mode, this pin is Receive Data 2 -.
17
4
DTR2* Data Terminal Ready 2 – Indicates Serial port 2 is powered, initialized,
and ready. Used as hardware handshake with DSR2 for overall readiness
to communicate.
18
9
NC
Not Connected (Ring Indicator 2)
19
5
GND
Ground
20
NC
NC
Not connected
Notes: The shaded area denotes power or ground. Signals are listed in the following order RS232 and
RS485/RS422.
Table 3-15. Serial B Interface Pin/Signal Descriptions (J13)
Pin #
Pin #
DB9
Signal
Description
1
1
(COM3)
DCD3* Data Carrier Detect 3 – 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 DTR3
as part of the DTR/DSR handshake.
2
6
DSR3* Data Set Ready 3 – Indicates external serial communications device is
powered, initialized, and ready. Used as hardware handshake with DTR3
for overall readiness to communicate.
3
2
RXD3
RX3-
Receive Data 3 – Serial port 3 receive data in
RX3- – If in RS485 or RS422 mode, this pin is Receive Data 3 -.
4
7
RTS3*
TX3+
Request To Send 3 – Indicates Serial port 3 is ready to transmit data.
Used as hardware handshake with CTS3 for low level flow control.
TX3+ – If in RS485 or RS422 mode, this pin is Transmit Data 3 +.
5
3
TXD3
TX3-
Transmit Data 3 – Serial port 3 transmit data out
TX3- – If in RS485 or RS422 mode, this pin is Transmit Data 3 -.
6
8
CTS3*
RX3+
Clear To Send 3 – Indicates external serial communications device is
ready to receive data. Used as hardware handshake with RTS3 for low
level flow control.
RX3+ – If in RS485 or RS422 mode, this pin is Receive Data 3 -.
7
4
DTR3* Data Terminal Ready 3 – Indicates Serial port 3 is powered, initialized,
and ready. Used as hardware handshake with DSR3 for overall readiness
to communicate.
8
9
RI3*
Ring Indicator 3 – Indicates external serial communications device is
detecting a ring condition. Used by software to initiate operations to
answer and open the communications channel.
9
5
GND
Ground
10
NC
KEY/
NC
Key
Not connected