Communication bus controller including designation of primary and secondary status according to slot position

A communications system comprising:

• one or more communication buses implemented on a backplane having one or more interface slots;
• one or more controller cards communicating with the communication buses through said one or more interface slots, each controller card comprising:
• a controller;
• and
• at least two independent communication channels provided for connecting a host with said one or more communication buses,
• wherein the controller determines and designate the status of said one or more controller cards such that:
• a first controller card is designated to have primary status if the first controller card is inserted in a first interface slot while remaining interface slots are empty;
• the first controller card in said first slot retains primary status while one or more controller cards are added or removed from said remaining slots:
• and
• a second controller card having a non-primary status inserted in a second interface slot assumes primary status after a power interruption, if the second interface slot is designated as the slot to assume primary status after a power interruption.