Serial (RS232) port information

    Pinout
    ------------------------------------------
    DB9  DB25  RJ45  Name  Description
    ------------------------------------------
     1     8     2   DCD   data carrier detect
     2     3     5   RD    receive data
     3     2     6   TD    transmit data
     4    20     3   DTR   data terminal ready
     5     7     4   SGND  signal ground
     6     6     1   DSR   data set ready
     7     4     8   RTS   request to send
     8     5     7   CTS   clear to send
     9    22     1   RI    ring indicator

    Pin IDs
      DB9    male: top 1->5,  bottom 6->9
      DB9  female: top 5->1,  bottom 9->6
      DB25   male: top 1->13, bottom 14->25
      DB25 female: top 13->1, bottom 25->14
      RJ45   male: top           view 1->8
      RJ45   male: front         view 8->1
      RJ45 female: front/outside view: 1->8
      RJ45 female: back/inside   view: top 8,6,4,2 bottom 7,5,3,1