Within each midlife instrument (Aquadopps, AquaPros, AWACs and Vectors) there is a wiring harness that connects the electronics board to the endbell, which specifies the comms protocol that the instrument uses. This harness can be either RS232 or RS422. The communications cable must then be chosen based on the harness type.
Changing from RS232 to RS422 and vice versa is a simple procedure that just requires the swapping of the harness and cable to the desired protocol.
If you have any problems when changing the harness, please contact Nortek Support.