All you have to learn about serial connector pinouts
RS-232 Connections That Work: Connecting Devices or Converters - Advantech
File:RS-232 Pinouts for the DE-9 Connector.svg - Wikimedia Commons
9 Pin Serial Pinout | Peatix
Sabrent USB 2.0 To Serial DB9 Male 9 Pin RS232 Cable Adapter CB-DB9P CBDB9P 819921011329 | eBay
4 Set Rs232 Serial Port Connector Db9 Female Socket Plug Connector 9 Pin Copper Rs232 Com Adapter With Plastic Case Diy Hy577 - Pc Hardware Cables & Adapters - AliExpress
RS232 Wiring
Communicating with Instruments using RS-232 | Keysight
rs232 9 pin pinout - Stratus Engineering
RS232 interface | RS232 pin diagram | DB25 | DB9
All you have to learn about serial connector pinouts