This pin diagram will be  useful when viewing these connectors. Sometimes you hold a soldering iron to the back of the connector, and you don’t remember the numbering of the pin. Here is the pin diagram for your reference:

rs232 com pinout circuit schematic

The number of each pins are actually  stamped on both sides of any D-type connector. Unfortunately, since they are only moldings, they are very difficult to see as they have no  color difference.