IBM PC/XT/AT RS-232 Serial Port Pin Configurations

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PC/XT Serial Cable Pin Connections

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D25-Pin RS-232

┌────┐ ┌────┐

│ 1 ├─────Protective Ground─────┤ 1 │

│ 2 ├───────Transmit Data──────>│ 2 │

│ 3 │<──────Receive Data────────┤ 3 │

│ 4 ├──────Request To Send─────>│ 4 │

│ 5 │<──────Clear To Send───────┤ 5 │

│ 6 │<─────Data Set Ready───────┤ 6 │

│ 7 ├───────Signal Ground───────┤ 7 │

│ 8 │<─────Carrier Detect───────┤ 8 │

│ 11 ├──────Select Standby──────>│ 11 │

│ 15 │<──Transmit Signal Timing──┤ 15 │

│ 17 │<──Receive Signal Timing───┤ 17 │

│ 18 ├───────────Test───────────>│ 18 │

│ 20 ├────Data Terminal Ready───>│ 20 │

│ 22 │<─────Ring Indicator───────┤ 22 │

│ 23 ├───────Speed Select───────>│ 23 │

└────┘ └────┘

PC/AT Serial Cable Pin Connections

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PC/AT

9-Pin RS-232

┌────┐ ┌────┐

│ 1 │<─────Carrier Detect───────┤ 8 │

│ 2 │<──────Receive Data────────┤ 3 │

│ 3 ├───────Transmit Data──────>│ 2 │

│ 4 ├────Data Terminal Ready───>│ 20 │

│ 5 ├───────Signal Ground───────┤ 7 │

│ 6 │<─────Data Set Ready───────┤ 6 │

│ 7 ├──────Request To Send─────>│ 4 │

│ 8 │<──────Clear To Send───────┤ 5 │

│ 9 │<──────Ring Indicator──────┤ 22 │

└────┘ └────┘

* NOTE: The Serial/Parallel adapter for the IBM PC/AT has a standard Parallel port and 9-pin (male) Serial port connector. The standard RS-232 cables for Serial devices cannot be connected to the Serial adapter without first converting the new configuration to the RS-232 configuration.

Standard RS-232-C Pin Assignments

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Circuit/

Pin No. Lead No. Description Direction

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1 AA/101 Protective Ground None

2 BA/103 Transmitted Data To DCE

3 BB/104 Received Data From DCE

4 CA/105 Request to Send To DCE

5 CB/106 Clear to Send From DCE

6 CC/107 Data Set Ready From DCE

7 AB/102 Signal Ground None

8 CF/109 Received Line Detect From DCE

9 ── For Testing

10 ── For Testing

11 **/116 Unassigned

12 SCF Second Received Line Detector From DCE

13 SCB Second Clear to Send From DCE

14 SBA Second Transmitted Data To DCE

15 DB/114 Transmitted Signal Timing From DCE

16 SBB Second Received Data From DCE

17 DD/115 Received Signal Timing From DCE

18 **/*** Unassigned

19 SCA Second Request to Send To DCE

20 CD/108.2 Data Terminal Ready To DCE

21 CG Signal Quality Detector From DCE

22 DE/125 Ring Indicator From DCE

23 CH/111 Rate Detector To DCE

24 DA Transmitted Signal Timing To DCE

25 ** Unassigned

David D. Scribner

2000-10-29T02:03:00