In this paper has been presented the way of design and implementation of WirelessHart in the work with the modified TrueTime simulator based on the MATLAB/Simulink, which can simulate the regulating and control mechanism in the execution of tasks in real-time systems, networks and dynamic plants. WirelessHart MAC protocol has been designed and implemented with some C++ functions with the suitable MATLAB MEX interfaces. For better understanding of MAC protocol in the work has been implemented the algorithm of pseudo-code.