The Sigma A-XT Ancillary Board is compatible with all Sigma A-XT control panels. The board provides volt-free, normally-open contacts, enabling control of sub-systems and plant remotely from the main panel over a two-wire data bus.

Ancillary boards require only a two-core data cable from the main control panel and a two-core power cable from the main panel.

Up to seven Ancillary boards can be connected to a control panel and each is allocated an address from one to seven using a binary coded DIL switch. The total length of
the data cable from the main panel to the last repeater must not exceed 4000 feet.

A mixture of status units and Ancillary boards, up to a maximum of seven of each type, can be connected to the serial data bus.