# RS232

Common names: EIA-232D (RS232-D), ITU-TSS (CCITT) V.24/V.28, ISO 2110

(at the DTE)
(at the DCE)

25 PIN D-SUB MALE at the DTE (Computer).
25 PIN D-SUB FEMALE at the DCE (Modem).

Pin | Name | RS232 | V.24 | Dir | Description
--- | --- | --- | --- | --- | ---
1 | GND | n/a | 101 |  | Shield Ground
2 | TXD | BA | 103 |  | Transmit Data
3 | RXD | BB | 104 |  | Receive Data
4 | RTS | CA | 105 |  | Request to Send
5 | CTS | CB | 106 |  | Clear to Send
6 | DSR | CC | 107 |  | Data Set Ready
7 | GND | AB | 102 |  | System Ground
8 | CD | CF | 109 |  | Carrier Detect
9 | - |  |  | - | RESERVED
10 | - |  |  | - | RESERVED
11 | STF |  | 126 |  | Select Transmit Channel
12 | S.CD | SCF | 122 |  | Secondary Carrier Detect
13 | S.CTS | SCB | 121 |  | Secondary Clear to Send
14 | S.TXD | SBA | 118 |  | Secondary Transmit Data
15 | TCK | DB | 114 |  | Transmission Signal Element Timing
16 | S.RXD | SBB | 119 |  | Secondary Receive Data
17 | RCK | DD | 115 |  | Receiver Signal Element Timing
18 | LL | LL | 141 |  | Local Loop Control
19 | S.RTS | SCA | 120 |  | Secondary Request to Send
20 | DTR | CD | 108.2 |  | Data Terminal Ready
21 | RL | RL | 140 |  | Remote Loop Control
22 | RI | CE | 125 |  | Ring Indicator
23 | DSR | CH | 111 |  | Data Signal Rate Selector
24 | XCK | DA | 113 |  | Transmit Signal Element Timing
25 | TI | TM | 142 |  | Test Indicator

Note: Direction is DTE (Computer) relative DCE (Modem).
Note: RS232 column is RS232 circuit name.
Note: ITU-T column is ITU-TSS V.24 circuit name.
Note: Do not connect SHIELD(1) to GND(7).

Contributor: Joakim Ögren, Petr Krc

Source:
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Copyright © The Hardware Book Team 1996-2001.
May be copied and redistributed, partially or in whole, as appropriate.
Document last modified: 2001-06-07