Cable Spec - DB9 RS232 Loopback Adapter
Written by Michael Cone
Updated at January 28th, 2026
This is the pinout for a DB9 RS232 Loopback adapter. Since DB9 serial ports are male gender (with pins), this adapter should be female.
Use this adapter with the Advanced Tubular Loopback Test program. (You can download the loopback tester from the main website or by using this link.)
Also, see how to use the loopback adapter: