Basic Model of a Real-time System

A computer system that is specially designed to work and respond the external events in a timely and predictable fashion is referred to as a real-time system. Read this tutorial to learn the basic model of a real-time system. But before that let’s have a look into the basics of a real-time system.

What is a Real-Time System?

A computer system that is capable of responding to external events in a timely and predictable fashion is referred to as a real-time system. Real-time systems are commonly used in various applications, such as industrial automation, robotics, automotives, medical instruments, scientific and engineering systems, and many more.

The real-time systems are known for their ability to respond to inputs within a certain time frame. However, the real-time systems require more complex system architecture to work correctly and safely.

Depending on the timing requirements in responding to inputs, there are two types of real-time systems namely, Hard Real-Time System and Soft Real-Time System.

The type of real-time systems whose timing requirements are very strict and missing a deadline can result in an extensive loss, such systems are referred to as a hard real-time system. Some common examples of hard real-time systems are medical instruments, automotive and flight control systems, etc.

On the other hand, the type of real-time systems that have flexible timing requirements and missing a deadline does not cause any serious loss, such systems are called soft real-time systems. The common examples of soft real-time systems are video conferencing systems, media systems, public telecommunication systems, etc.

A real-time system takes inputs through sensors, and other external input devices, then processes these input signals in real-time to produce output. Therefore, a real-time system is implemented with the help of a variety of hardware components and software applications.

Now, let us understand the basic model of a real-time system in detail.

Basic Model of a Real-Time System

The basic model of a real-time system consists of the following three major components −

The Operating Environment

The operating environment of a real-time system is the world external to the system from where input signals are received. The operating environment of a real time system is modeled as a collection of input events that occur over time.

The Controlled System

The controlled system of a real-time system is typically a computing unit that can process input signals received from the operating environment to produce the output signals. It composed of several hardware and software components that perform processing of input signals-based instructions.

The Feedback System

The feedback system of a real-time system is a system of hardware and software components, allowing the system to respond the variations in the inputs and outputs in real-time manner. It consists of two major parts; one is feedback controller and another is feedback mechanism.

The feedback mechanism monitors the variations in the output of the system and compare it with a reference signal. If there is a difference between the sampled signal and reference signal, then a corrective action is taken by the feedback controller to bring the output signal to its desired level.

In addition to the above three components, a practical real-time system also consists of several other components like communication system, performance monitoring system, signal conditioning systems, input and output interfaces, etc.

Here, the communication system is responsible for transferring data within the system or between different connected system in real time. The performance monitoring system analyzes and improves the performance and efficiency of the system. Signal conditioning systems are responsible for converting physical events into electrical signals and vice-versa. There are two types of signal conditioning systems namely, input conditioning system (for conditioning the electrical signals receiving from sensors) and output conditioning system (for conditioning the electrical signals receiving from the computing unit).

The interfaces are required for converting signals into the desired form, i.e. analog to digital and digital to analog. There are two types of interfaces are used in a real-time system namely, input interface (for converting physical events that are analog signals into digital signals) and output interface (for converting digital signals coming system to analog signals).

Conclusion

In conclusion, the basic model of a real-time system consists of a variety hardware and software components for processing of signals received from external events in a timely and predictable manner. Today, the real-time systems are being used in a variety of applications such as automation, communication, robotics, weather forecasting, scientific and engineering applications, medical devices, automotives, etc.