As the capability to automatically generate code from different models becomes more sophisticated, it is critical that these models be adequately tested for quality assurance prior to code generation. Although simulation-based blackbox testing strategies exist for these models, it is important that we also employ white-box testing strategies similar to those used to test implementation code. More precisely, we apply coverage testing to architectural design models represented by SDL (Specification and Description Language). Our previous study [30] defined a methodology for automatic test generation with respect to structural-based criteria such as all-node and all-edge. Now, we propose new coverage criteria such as n-step message transfer and sender-receiver round-trip, aiming at the communication between SDL processes.