|
The most common connectors for RS232 communication are
| • | 9-pole SUB D9 (EIA/TIA 574 standard). Introduced by IBM and widely used. See below. |
| • | 25-pole SUB D25 (RS232-C). This is the original connector introduced for the RS232 standard. It provides a secondary communication channel. |
| • | 8-pole RJ45 (RS232-D, according to EIA/TIA-561 standard). |
RS232 SUB D9 Pinout
View: Looking into the male connector.
Pinout: From a DTE perspective (the DTE transmits data on the TX Transmit Data line, while the DCE receives data on this line)
Pin No.
|
Signal Name
|
Description
|
DTE in/out
|
1
|
DCD
|
Data Carrier Detect
|
Input
|
2
|
RX
|
Receive Data
|
Input
|
3
|
TX
|
Transmit Data
|
Output
|
4
|
DTR
|
Data Terminal Ready
|
Output
|
5
|
SGND
|
Signal Ground
|
-
|
6
|
DSR
|
Data Set Ready
|
Input
|
7
|
RTS
|
Request To Send
|
Output
|
8
|
CTS
|
Clear To Send
|
Input
|
9
|
RI
|
Ring Indicator
|
Input
|
RS232 SUB D25 Pinout
View: DTE perspective, looking into the male connector
Pin No.
|
Signal Name
|
Description
|
1
|
-
|
Protective/Shielding Ground
|
2
|
TX
|
Transmit Data
|
3
|
RX
|
Receive Data
|
4
|
RTS
|
Request To Send
|
5
|
CTS
|
Clear To Send
|
6
|
DSR
|
Data Set Ready
|
7
|
SGND
|
Signal Ground
|
8
|
DCD
|
Data Carrier Detect
|
9
|
-
|
Reserved
|
10
|
-
|
Reserved
|
11
|
-
|
Unassigned
|
12
|
SDCD
|
Secondary Data Carrier Detect
|
13
|
SCTS
|
Secondary Clear To Send
|
14
|
STx
|
Secondary Transmit Data
|
15
|
TxCLK
|
Transmit Clock
|
16
|
SRx
|
Secondary Receive Data
|
17
|
RxCLK
|
Receive Clock
|
18
|
LL
|
Local Loopback
|
19
|
SRTS
|
Secondary Request To Send
|
20
|
DTR
|
Data Terminal Ready
|
21
|
RL/SQ
|
Remote Loopback / Signal Qualify Detector
|
22
|
RI
|
Ring Indicator
|
23
|
CH/CI
|
Signal Rate Selector
|
24
|
ACLK
|
Auxiliary Clock
|
25
|
-
|
Unassigned
|
RS232-D, RJ45 pinout
Pin No.
|
Signal Name
|
Description
|
1
|
DSR / RI
|
Data Set Ready / Ring Indicator
|
2
|
DCD
|
Data Carrier Detect
|
3
|
DTR
|
Data Terminal Ready
|
4
|
SGND
|
Signal Ground
|
5
|
RX
|
Receive Data
|
6
|
TX
|
Transmit Data
|
7
|
CTS
|
Clear To Send
|
8
|
RTS
|
Request To Send
|
| 
