The paper presents a study of generating test sequences for the SCSI (Small Computer Systems Interface) interface. For this purpose a special conformance test generator has been developed. The paper describes the conformance testing algorithm and the conditions that are assumed for the tests. Test generation method is based on UIO (Unique Input Output) technique which is an unambiguous state identification method. Test cases are generated using FSM (Finite State Machine) model of the analysed protocol. The FSM model has been obtained by the detailed transformation of SDL protocol representation. The result of the conversion is an argument for test generator. The final product of the generator is expressed in TTCN notation.