This paper presents rapid prototyping of networked embedded systems by the method that employs hardware and software components and an eligible executable specification language. Statements of that language should cover process management, timing and communication commands interpretable by the services of a real-time executive and a communication task located in each prototype node. The language is made executable by a technique that employs attribute grammars and either macroprocessor or Prolog-supported generation of communication software prototypes. Execution or interpretation of the expanded code embedded in reusable system components of the trial architecture provides final steps of the method. In the paper, an introduction to a dedicated asynchronous specification language is followed by a review of related prototyping techniques. The included case study deals with an application of the language for two-level specification of an Internet-based device for pressure measurement.