Developing and testing complex information technology (IT) systems is a difficult task. This is even more difficult if parts of the system, no matter if hard- or software, are not available when needed due to delays or other reasons. The architecture and design cannot be evaluated and existing parts cannot be reliably tested. Thus the whole concept of the system cannot be validated before all parts are in place. To solve this problem in an industrial project, where the development of the server-side should be finished and tested (clear for production) while the hardware sensors where designed but not implemented, we developed an emulator (software) for the hardware sensors meeting the exact specification as well as parts of the server solution. This allowed proceeding with the server-side development, testing, and system validation without the hardware sensors in place. Following the exact specification should allow replacing the emulator with the real sensors without complications, once they are available. In the end, being able to develop hard- and software in parallel the project can be in production much earlier than performing the development in sequence.