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)
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)
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 |