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EIA/TIA RS-232 Reference

Pin RS232 Dir Description
1 GND - Shield Ground
2 TXD O Transmit Data
3 RXD I Recieve Data
4 RTS O Request to Send
5 CTS I Clear to Send
6 DSR I Data Set Ready
7 GND - System Ground
8 CD I Carrier Detect
9 - - RESERVED
10 - - RESERVED
11 - - UNASSIGNED
12 S.CD I Secondary Carrier Detect
13 S.CTS I Secondary Clear to Send
14 S.TXD O Secondary Transmit Data
15 TXC O Transmission Signal Element Timing
16 S.RXD I Secondary Recieve Data
17 RXC I Reciever Signal Element Timing
18 - - UNASSIGNED
19 S.RTS O Secondary Request to Send
20 DTR O Data Terminal Ready
21 SQD I Signal Quality Detector
22 RI I Ring Indicator
23 SS - Data Signal Rate Selector
24 TXC - Transmit Signal Element Timing
25 - - UNASSIGNED

DB-25 Connector. DTE Male Connector


Data Communications for Businesses