As the complexity of the systems increases, so does the complexity of designing a suitable engineering IT architecture. Challenges reach from the definition of required and consistent functionalities and interfaces to the evaluation, which combination of IT tools fulfils the required functionality, usability and interoperability in the best way. Thus, we provide a procedure, methodology and modelling support for the definition of functional and logical engineering IT architectures and their holistic evaluation. The approach is part of an overall procedure and demonstrated in an example.