Use what you already have.
For some serial applications, sockets are required instead of plugs. With this adapter you can inexpensively change the polarity (the "gender") of the connection. This protects the environment and your wallet.
 
Technical data:
Connection type: Serial
Connection A number: 1x
Connection A: D-SUB socket 9-pin
Connection B number: 1x
Connection B: D-SUB socket 9-pin
Execution: Adapter
Manufacturer color: Yellow
Plug version: Straight
Particularities: Screwable
Cable application: Serial
Product Type: Serial adapter