PACKET RADIO: RS-232 Pinouts

Steve Wolf, W8IZ@W8IZ


(This text from the W8IZ packet radio bulletin

board. It's formatted to fit a 80 character screen.)


   Common name   RS232C Name          Description
 
25pin         9 pin        DCE Direction
1                       AA      x       Protective Ground
2       TXD     3       BA      I       Transmitted Data
3       RXD     2       BB      O       Received Data
4       RTS     7       CA      I       Request to Send
5       CTS     8       CB      O       Clear to Send
6       DSR     6       CC      O       Data Set Ready
7       GND     5       AB      x       Signal Ground
8       CD      1       CF      O       Received Line Signal Detector
9                       --      x       Reserved for Data set Testing
10                      --      x       Ditto
11                              x       Unassigned
12      SCF                     O       Secondary Received Line Signal                                          Detector
13      SCB                     O       Secondary Clear to send
14      SBA                     I       Secondary Transmitted Data
15      DB                      O       Transmission Signal Element                                             Timing  (DTE Source)
16      SBB                     O       Secondary Received Data
17      DD                      O       Receiver Signal Element Timing                                          (DCE Source)
18                              x       Unassigned
19      SCA                     I       Secondary Request to Send
20      DTR     4       CD      I       Data Terminal Ready
21      CG                      O       Signal Quality Detector
22              9       CE      O       Ring Indicator
23      CH/CI                   I/O     Data Signal Rate Selector                                               (DTE/DCE Source)
24      DA                      I       Transmit Signal Element Timing (DTE Source)
25                              x       Unassigned

How to wire a Nullmodem cable
 
                25pin   9pin            9p      25p
FG              1       -       X       -       1       FG
TD              2       3       -       2       3       RD
RD              3       2       -       3       2       TD
RTS             4       7       -       8       5       CTS
CTS             5       8       -       7       4       RTS
SG              7       5       -       5       7       SG
DSR             6       6       -       4       20      DTR
DTR             20      4       -       6       6       DSR
 ---------------------------------------------------------------------------
Frame Ground
Transmit Data
Receive Data
Request To Send
Clear To Send
Signal Ground
Data Set Ready
Data Terminal Ready 

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