Efficient communication of data between blocks in a high level modeling system

A method communicates data with efficient conversion between representations in a high-level modeling system. The data is communicated from a first block in a first external format and the data is communicated to a second block in a second external format. The first block has a first internal representation of the data and the second block has a second internal representation of the data. The first internal representation is converted to the second internal representation without intermediate representation in the first and second external formats in response to different first and second external formats or different first and second internal representations. Conversion between the representations of the data is bypassed in response to like first and second external formats and like first and second internal representations. A signal instance is created that communicates the data between the blocks. Converters between data representations are installed in the signal instance on demand.