RS232 Connectors / Pinout

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RS232 Connectors / Pinout

The most common connectors for RS232 communications 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 (different pinouts for Cisco/Yost wiring, EIA/TIA-561, and other manufacturer-specific pinouts).

 

 

RS232 SUB D9 (D-Sub DB9) 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)

 

DL-SubD9-male-SW

 

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 (D-Sub DB25) Pinout

 

View: Looking into the male connector.

Pinout: From a DTE perspective.

 

DL-SubD25-male-SW

 

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

 

 

 

RJ45 8-pole pinouts

 

 

PT_connector_rs232rj45

 

Several conflicting pinouts exist and are in use for RJ45 connectors in RS232 communications:

 

Cisco Console / Yost Cable / Rollover cable applications

 

Pinout: From a DTE perspective (the DTE transmits data on the TX Transmit Data line)

 

Pin No.

Signal Name

Description

1

CTS

Clear To Send

2

DCD

Data Carrier Detect

3

RX

Receive Data

4

SGND

Signal Ground

5

SGND

Signal Ground

6

TX

Transmit Data

7

DTR

Data Terminal Ready

8

RTS

Request To Send

 

NOTE: The Cisco/Yost pinout is used with cables that are wired "mirror image" on one end., similar to a Null Modem Cable with Handshaking. Every device has the same RJ45 female socket and transmits data on the same pin. See also the Yost Serial Device Wiring Standard .

 

EIA/TIA-561 standard for RJ45 / 8P8C modular connector

 

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

 

NOTE: Though this is an official standard, it is more likely that you will find RS232 RJ45 products with different pinout, either the Cisco/Yost variant above or manufacturer-specific pinouts, e.g. MOXA Nport.