RS-232 Interface

RS-232 (EIA Std.) applicable to the 25 pin interconnection of Data Terminal Equipment (DTE)
and Data Communications Equipment (DCE) using serial binary data.
Pin Signal EIA
1 Frame Ground AA    
2 Transmitted Data BA   D (Data)
3 Received Data BB D  
4 Request to Send CA   C (Control)
5 Clear to Send CB C  
6 Data Set Ready CC C  
7 Signal Gnd/Common Return AB    
8 Rcvd. Line Signal Detector CF C  
11 Undefined      
12 Secondary Rcvd. Line Sig. Detector SCF C  
13 Secondary Clear to Send SCB C  
14 Secondary Transmitted Data SBA   D
15 Transmitter Sig. Element Timing DB T (Timing)  
16 Secondary Received Data SBB D  
17 Receiver Sig. Element Timing DD T  
18 Undefined      
19 Secondary Request to Send SCA   C
20 Data Terminal Ready CD   C
21 Sig. Quality Detector CG   C
22 Ring Indicator CE C  
23 Data Sig. Rate Selector (DCE) CI   C
24 Transmitter Sig. Element Timing DA   T
25 Undefined