- RS232 Pinout, Direction & signal Levels -

EIA-232-E  (RS-232)
FUNCTION
Pin #
DB-25
Pin #
DB-9
EIA-530
FUNCTION
Pin #
DB-25
TO
DTE
TO
DCE
Shield 1   Shield 1    
Transmit Data  (TD) 2 3 Transmit Data  (A)
                          (B)
2
14
   >
Receive Data  (RD) 3 2 Receive Data  (A)
                         (B)
3
16
 <  
Request To Send  (RTS) 4 7 Request To Send  (A)
                               (B)
4
19
   >
Clear To Send  (CTS) 5 8 Clear To Send  (A)
                          (B)
5
13
 <  
DCE Ready  (DSR) 6 6 DCE Ready  (A)
                      (B)
6
22
 <  
Signal Ground  (SG) 7 5 Signal Ground  (A) 7    
Received Line Signal Detector  (DCD) 8 1 Received Line   (A)
Signal Detector (B)
8
10
 <  
DTE Ready  (DTR) 20 4 DTE Ready  (A)
                      (B)
20
23
   >
Ring Indicator  (RI) 22 9 N/A      -

 
 
 - Signal Level -
Signal State
Threshold Voltages
  Signal with respect to SG Signal A with respect to Signal B 
  RS-232 RS-422 RS-485
"0", Asserted, ON,  Space, Active +3 to +25 VDC +2 to +6  VDC  (Trasmit)
+0.2 to +7 VDC  (Receive)
+1.5 to +6 VDC (Transmit)
+0.2 to +12 VDC (Receive)
"1", Desasserted, OFF,  Mark, Inactive -3 to -25 VDC -2 to +6 VDC  (Transmit)
-0.2 to -7 VDC (Receive)
-1.5 to -6 VDC (Transmit)
-0.2 to -7 VDC (Receive)

 
 

Copyright © 2002-2008  Ted J. Mieske
All Rights Reserved.