DB-9F DB-25M Function.
1 to 8 Data Carrier Detect (DCD).
2 to 3 Receive Data (RD or Rx).
3 to 2 Transmit Data (TD or Tx).
4 to 20 Data Terminal Ready (DTR).
5 to 7 Signal Ground (SGND or Gnd).
6 to 6 Data Set Read (DSR).
7 to 4 Request To Send (RTS).
8 to 5 Clear To Send (CTS).
9 to 22 Ring Indicator (RI).