Bus Loading Associated Software Tools
BLAST - an apt acronym for Bus Loading Associated Software Tools, is a software system which encompasses various Bus related modules. It helps in creating and maintaining the necessary databases required by software like Bus driver and Remote Terminal (RT) emulation. The independent modules of this system are RTC, message creation, off-line scheduler and message analysis.

The BLAST Environment

There are three dual redundant buses integrating the subsystems. Each subsystem is connected to atleast one bus and not more than two buses. Every bus is controlled by a Bus Controller, in short called as BC. There are RTs hooked on to each of these buses.

Some RTs, depending on their importance or need for interaction with others, might be on two buses. There is an Input/Output processor which controls and monitors the activities on all the three buses. This is an 80386 CPU which will, in the final system, interact with the main computer.

Looking at software, the Off-line scheduler would run on any PC and would generate files that assist the runtime scheduling. The RTC and message creation modules help in maintaining the necessary databases for preparing this schedule. The bus driver software would reside on the I/O processor and would monitor and control the entire bus traffic.

The bus traffic can be captured and analysed using the Message Analysis software.

BLAST would be used to define, manage and control the communication between various subsystems connected to the 1553B Buses. 1553B is a standard that defines the concept of operation and information flow on the data bus. It also defines the functional formats to be employed. The various subsystems have their own or shared remote terminals, which act as their front end, interfacing them with the Bus.

If one were to put in a nut-shell, the following would be the operations that BLAST would perform for the avionics communication system. RTC, the major component of BLAST, would maintain information on the various Remote Terminals in the system. The words that are defined in RTC are picked to form the messages of the avionics system. These messages are then scheduled offline to obtain a compact file that could be used by the Bus driver. During real-time, the message transacted can be captured and analysed using the Message analysis modules. BLAST has a report generation module which prints the ICD in the report form.