The ATC-863/871 comes with a default setting of 9600 baud, and No Parity at Channel 1. If your equipment is set to work at these settings then you can plug in two units and send data without changing the configuration. The 863/871 units will communicate with all other units set to the same channel. If you add a third adapter to the network they will all intercommunicate. Data sent from one unit will be received on all other units at that channel.
If you need to change any of the settings then it will require setting up the units using the RF Module software included on the product CD.