Rapid developments in networking technologies is resulting in an increasing number of new communication protocols being created, but formal methods are seldom used to verify their design. This paper presents a set of rules for transforming state tables, a common format of protocol specifications in standards, into a formal model based on Coloured Petri nets. This reduces time for developing and debugging CPN models, which can then be used for protocol verification. Formal definitions of subsets of state tables and CPNs are presented, as well as the transformation algorithm. To demonstrate the transformation an example of Stop-and-Wait protocol is used as a case study.