A recent trend in embedded industry is to mix Integrated Modular Architectures (IMA) with Time Sensitive Networking (TSN). IMA principles allow resource sharing between numerous software functions in a deterministic way. On the other side TSN is considered a promising communication solution for distributed architectures. However, TSN has not been fully exploited with IMA, while it would meet the increasing communication needs due to the explosion of the number of on-board software functions. In order to better understand the challenges of designing IMA-TSN systems, this paper proposes a joint model which unifies task and message management and allows evaluation of end-to-end latency properties. The model is illustrated by simulation on an avionic case study.