Abstract-This paper aims to explicate the method for test case generation in real-time systems. In software engineering, software design phase has the diagrammatic way to understand the real-time systems. The process of software testing to identify the defects and uncovered error as much as possible. Testing the real-time systems has more difficult process because the real-time system programs are adjacent to the hardware device. In this real -time system controls an environment by receiving data, processing and returning the processed data. These systems are simulation process with timing constraint so effective path coverage criteria are required. The testing may be poorly implemented which shows in a low-quality software or more time and cost wastage. A test case plays an important role in software testing. The applicable test cases have been used for generation of test scenarios and test data for realtime systems. This survey puts forward a discussion of research approaches and techniques based on functional specification i.e. behavioural diagram based test cases and structural diagram based test cases. This paper has been classifying the various intermediate approaches that are used to generate a test case for real -time systems notwithstanding discuss the test coverage criteria and major issues applicable to these approaches.Keyword-Real -time system, Model based test case generation, Embedded system I. INTRODUCTION In the real-time digital world, the software has played an important role in our society. We are increasingly dependent on software because the software to run perfectly in our day to day lives. Real-time software needs perfect testing during the software development phase. The software can be tested either automatically or manually. A traditional testing method based on hand work is low efficiency and carried out more time and cost. Automated software testing are consumes more than 50% of the costs that are associated with the software development. Automated software testing can bring us a lot of advantages, which make it easier to find bugs. The automated testing is fully based on test cases. Over the past years, the test case generation approaches have faced many trials to produce efficient automated test cases [1]. The research community presented many approaches to generate the test cases from the functional specification. The design specification allows trimming the error in the early stage of software development. The real-time systems to be coupled with behavioural and structural specifications. An embedded system generally uses microprocessors and integrated circuits that contain many functions. Most of the embedded systems designed for life or safety critical system. The effective path coverage is required in the development process. The execution of embedded real-time system with an object-oriented program is expressed to represent a dynamic view of behaviour and structural in Unified Modelling Language (UML) and some of the structural specification in the Functional block diagram (F...