Modular pool/spa control system

A pool or spa control system, comprising:

• a main control panel defining a housing;
• a motherboard housed in the main control panel, said motherboard including a motherboard processor, an internal bus, and a relay bank socket, the internal bus establishing two-way communication between the motherboard processor and the relay bank socket;
• a relay bank connectable to the relay bank socket and including a relay bank processor, a memory, an internal bus, a plurality of relays, and a connector, the internal bus establishing two-way communication between the relay bank processor and the motherboard processor when the relay bank is connected to the relay bank socket via the connector;
• a local terminal including a control processor, a user interface, and a memory, the local terminal being in two-way communication with the motherboard processor for allowing a user to control the system,
• wherein (i) said control processor communicates with said relay bank processor while said relay bank is connected with said relay bank socket of said motherboard, (ii) said control processor automatically discovering the relay bank and assigning a network address to the relay bank, (iii) said relay bank automatically sending the control processor information regarding parameters of said relay bank upon discovery, and (iv) said control processor storing the information received from the relay bank into the memory of the local terminal.