The DB9F-TO-RJ45 Adapter plugs into a normal DSub-9 male serial port
This way it allows to use a Cat5 cable for data transmission. This is very effective
when using RS422 or RS485 operation, since the differential signals are located on
the paired wires.
The matching adapter DB9M-TO-RJ45 at the other end of the Cat5 cable reverses the
conversion, the standard signal assignment is valid again.
But customers may use their own connection on the other side.