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RS232

25 PIN D-SUB MALE (At the DTE)
25 PIN D-SUB FEMALE (At the DCE)

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

Pin Name ITU-T Dir Description
1 GND 101 --- Shield Ground
2 TXD 103 --> Transmit Data
3 RXD 104 <-- Receive Data
4 RTS 105 --> Request to Send
5 CTS 106 <-- Clear to Send
6 DSR 107 <-- Data Set Ready
7 GND 102 --- System Ground
8 CD 109 <-- Carrier Detect
9 -   - RESERVED
10 -   - RESERVED
11 STF 126 --> Select Transmit Channel
12 S.CD ? <-- Secondary Carrier Detect
13 S.CTS ? <-- Secondary Clear to Send
14 S.TXD ? --> Secondary Transmit Data
15 TCK 114 <-- Transmission Signal Element Timing
16 S.RXD ? <-- Secondary Receive Data
17 RCK 115 <-- Receiver Signal Element Timing
18 LL 141 --> Local Loop Control
19 S.RTS ? --> Secondary Request to Send
20 DTR 108 --> Data Terminal Ready
21 RL 140 --> Remote Loop Control
22 RI 125 <-- Ring Indicator
23 DSR 111 --> Data Signal Rate Selector
24 XCK 113 --> Transmit Signal Element Timing
25 TI 142 <-- Test Indicator
Note: Direction is DTE (Computer) relative DCE (Modem).
Note: Do not connect SHIELD(1) to GND(7).
Contributor: Joakim Ögren, Petr Krc
Source: ?
Please send any comments to Joakim Ögren.