The inputs and outputs of the communications blocks support various data types. For some blocks, changing to single outputs can lead to different results when compared with double outputs for the same set of parameters. Some blocks may naturally output different data types than what they receive (e.g. digital modulators) a signal. Refer to the individual block reference pages for details.
The Simulink Block Data Type Support for Communications Toolbox™ table provides details regarding capabilities and limitations
pertaining to code generation, variable-sizing, and supported data types for all
Communications Toolbox blocks. To access the table, type
showcommblockdatatypetable at the MATLAB® command line.