In the market there are the following types of Serial - RJ45 Cables.
Pin1 = CTS | Pin2 = DSR | Pin3 = RX | Pin4 = GND
Pin5 = GND | Pin6 = TX | Pin7 = DTR | Pin8 = RTS
When attached to a Beige RJ45 to DB9 Adaptor which we sell, the pins are translated as per below drawing.
For the Null adapter