A Tool for Generating Automata of IEC60870-5-104 Implementations

Power distribution networks are often controlled using the communication protocol IEC 60870-5-104 (IEC-104). While a specification exists, not every device implementing this protocol, actually follows this specification. We present \textit{mealy104}, a tool that infers finite-state automata from IEC-104 implementations and use it on a real device implementing IEC-104, comparing it to the protocol standard. We use the tool to show that implementations do deviate from the specification