Real Time Systems and Design

 

All real time systems are on-line and are triggered by the response to the external events like the information systems in batch mode.  A real time system must also integrate the hardware, the software, the user and the database to achieve certain results with an acceptable performance.

 

The real time systems have the following design components:

 

• Data acquisition
• Measurement, interpretation and evaluation
• Decision making and action
• Initialization, operation and control.

 

The real time, systems are developed for diverse applications in the process control, process automation, medical and scientific research traffic management, aerospace systems and instrumentation. In all these applications, the real time system responds to the external stimulate in a time which is governed by the external world. Hence, the performance of the real time system depends on the speed of its performance.

 

The entire cycle of acquisition, measurement, evaluation, decision making, action, control and bringing the system back to  the initial condition is highly time sensitive. If this cycle is not performed in a time within which no damage is possible then the system performance is acceptable.  Failing this, the real time system needs re-look and redesign in most of the applications, the real time systems are many and they are organized to obtain certain output. They are dependent on each other and some of them run in parallel and some in sequence. Some of these work on priority which is in-built in the total application design.

 

In the real time systems are analyzed in an industrial application or in the business commercial application, it will be found that their functional requirements are same.  They are as follows:

 

• Interface handling with the external world
• Context switching after the measurement
• Prime response time
• Data management
• Resource allocation by priority
• Task synchronization and communication

 

The real time systems are designed first with a prototype and then rigorously tested through simulation processes to confirm the accuracy in handling the following features:

 

• Triggers and context switching on condition
• Concurrency of the data and processes
• Communication and synchronization
• Timing constraints attached to the tasks
• Coupling of the processes and actions

 

The real time software system has all the aspects of the conventional system design and in addition it has to handle a new set of requirements arising out of the real time feature.  The real time software is either time or event driven and hence the hardware and software which deals with these parameters gather a lot of importance in design of the system.