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ActiveXperts.com » Serial Port Component » Tutorials » RS423

RS423 Serial Port Connector Pin Layout

RS-423 is a serial communications standard that provides asynchronous communication capabilities, such as hardware flow control, software flow control, and parity check. It has been widely used for decades. Unlike RS-232, RS-423 is capable of data transmissions over long distances (up to 4000 Feet).

The following document describes the functions of the pins on the RS423 25 and 37 pin Sub-D connectors used in serial communications. The pins in the images are as viewed from the pin side (not the solder or printed circuit board side). The male sockets are used on the DTE (Data Terminal Equipment ) or PC side. The female sockets are on the DCE (Data Communication Equipment ) or Modem Side.

Using the ActiveXperts Serial Port Component you can send and receive data and control the RS423 port.

RS423 25 Pin connector (DB-25)

RS423 25 Pin connector (DB-25)
1 GND Shield
2 TDA Transmitted Data A
3 RDA Received Data A
4 RTSA Request To Send A
5 CTSA Clear To Send A
6 DSRA Data Set Ready A
7 GND Signal Ground
8 RLSDA Receive Line Signal Detect A
9 RTA Receive Timing A
10 RLSDB Receive Line Signal Detect B
11 XTB External Timing B
12 TTB Transmit Timing B
13 CTSB Clear To Send B
14 TDB Transmit Data B
15 TTA Transmit Timing A
16 RDB Received Data B
17 RTA Receive Timing A
18 LL Local Loopback
19 RTSB Request To Send B
20 DTRA Data Terminal Ready B
21 RL Remote Loopback
22 DSRB Data Set Ready B
23 DTRB Data Terminal Ready B
24 XTA External Timing A
25 TM Test Mode Indicator

RS423 37 Pin connector (DB-37)

RS423 37 Pin connector
1 GND Ground
2 SRI Signal Rate Indicator
3 - Reserved
4 TDA Transmit Data A
5 TTA Transmit Timing A
6 RDA Received Data A
7 RTSA Request To Send A
8 RTA Receive Timing A
9 CTSA Clear To Send A
10 LL Local Loopback
11 DSRA Data Set Ready A
12 DTRA Data Terminal Ready A
13 RLSDA Receive Line Signal Detect A
14 RL Remote Loopback
15 IC Incoming Call
16 SF Select Frequency
17 XTA External Timing A
18 TMI Test Mode Indicator
19 GND Ground
20 RC Receive Common
21 - Not Connected
22 TDB Transmit Data B
23 TTB Transmit Timing B
24 RDB Receive Data B
25 RTSB Request To Send B
26 RTB Receive Timing B
27 CTSB Clear To Send B
28 TIS Terminal In Service
29 DSRB Data Set Ready B
30 DTRB Data Terminal Ready B
31 RLSDB Receive Line Signal Detect B
32 SS Select Standby
33 SQ Signal Quality
34 NS New Signal
35 XTB External Timing B
36 SB Standby Indicator
37 SC Send Common