With the use of MATLAB-SIMULINK a simple tool has been developed to compute the controllabilities of nodes as well as branches of digital system networks. The primary advantage of this tool may be for such conditions where the study of controllability analysis of a system with different possible designs is required to give an optimal design solution. The ease of network simulation procedures together with the simple methodologies for inputting the different assigned parameters to the respective elements of the system in dynamic environments, are additional attributes of this tool.