This specification covers the requirements, examinations and tests for the Distribution Box Built-In-Test (BIT) circuit card assembly, herein after referred to as the Distribution Box BIT Board (DBB). The DBB circuits are used to communicate cannon control voltages and mount hatch protection circuits data to the Fire Control Processor (FCP). Data transmission is non-continuous and reception is serially formatted through a Universal Asynchronous Receiver Transmitter (UART) link which is enabled by the FCP Central Processing Unit (CPU) . DBB contains twelve microcircuits and resistive, capacitive, and semi-conductive circuitry. The DBB is a 4 by 8 1/2 inch double-layered circuit card mounted vertically in the Distribution Box. Refer to Figure 1 for the Distribution Box BIT assembly functional block diagram (see 6.1).
