Specifications

Chapter 3 Hardware
LittleBoard 800 Reference Manual 23
Note: The shaded area denotes power or ground. Signals are listed in the table with RS232 first, followed
by RS485/RS422.
68CTS1*
RX1+
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+ – If in RS485 or RS422 mode, this pin is Receive Data 1 -.
7 4 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.
8 9 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.
95
GND Ground
10 NC KEY/
NC
Key
Not connected
11 1
(COM2)
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.
12 6 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.
13 2 RXD2
RX2-
Receive Data 2 – Serial port 2 receive data in.
RX1- – If in RS485 or RS422 mode, this pin is Receive Data 1 -.
14 7 RTS2*
TX2+
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+ – If in RS485 or RS422 mode, this pin is Transmit Data 2 +.
15 3 TXD2
TX2-
Transmit Data 2 – Serial port 2 transmit data out
TX2- – If in RS485 or RS422 mode, this pin is Transmit Data 2 -.
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 1 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
Table 3-5. Serial A Interface Pin/Signal Descriptions (J11) (Continued)