The signals available are:
¾
TX data (TX / CT103),
¾
RX data (RX / CT104),
¾
Request To Send (RTS / CT105),
¾
Clear To Send (CTS / CT106),
¾
Data Terminal Ready (DTR / CT108-2),
¾
Data Set Ready (DSR / CT107).
The 2 additional signals are Data Carrier Detect (DCD / CT109) and Ring
Indicator (RI / CT125).
fig. 6 RS232 Serial Link signals
RS232 interface has been designed to allow a certain flexibility in the use of
the serial interface signals. However, the use of TX, RX, CTS and RTS signals
is mandatory which is not the case for DTR, DSR, DCD and RI signals which
can be not used.
2.2.2 Pin out description
Signal
Pin #
I/O
I/O type
RS232 STANDARD
Description
TX / CT103
2
O
TX
Transmit serial data
RX / CT104
3
I
RX
Receive serial data
RTS / CT105
8
I
RTS
Request To Send
CTS / CT106
7
O
CTS
Clear To Send
DSR / CT107
6
O
DSR
Data Set Ready
DTR / CT108-2
4
I
DTR
Data Terminal Ready
DCD / CT109
1
O
DCD
Data Carrier Detect
RI / CT125
9
O
RI
Ring Indicator
GND / CT102
5
-
GND
Ground
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