Testing of a software product is the key activity before deploying it in the real-time environment. Therefore testing should be introduced into the product development process as early as possible in order to decrease the costs of repairing the damage in later phases. In this paper we use Coloured Petri Nets (CPN) for the system specification and also as a system to be tested instead of its implementation. This specification also serves as the basis for the test suite generation. Test cases are provided in the language of Testing and Test Control Notation version 3 (TTCN-3) due to its general application area and platform independence.