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