The emerging OMG UML Profile for Modeling and Analysis of Real-Time Embedded systems (MARTE) aims, amongst other things, at providing a referential Time Model subprofile where semantic issues can be explicitly and formally described. As a full-size exercise we deal here with the modeling of immediate and delayed data communications in AADL. This actually reflects an important issue in RT/E model semantics: a propagation of immediate communications may result in a combinatorial loop, with ill-defined behavior; introduction of delays may introduce races, which have to be controlled. We describe here the abilities of the MARTE time model in this respect.