IEC 60870-5-104 (or IEC 104 for short), derived from the well-known IEC 101, is a communication protocol of the IEC 60870-5 standard.
A set of standards that define the systems/s and/or method/s used for telecontrol (supervision and data acquisition) in electrical engineering and automation applications of sub-stations, primary stations, power plants, etc.
This protocol is an extension of IEC 60870-5-101 (IEC 101). In fact, unlike IEC 101, it uses the TCP/IP standard as a communication means (Link and Physical layer). This guarantees greater flexibility in WAN (Wide Area Network) and LAN (Local Area Network) applications, the use of different communication technologies (ISDN, X.25, Frame relay etc.), as well as better performance.
The application layer of IEC 104 is the same as that of IEC 101, except for some slight differences. Some ASDU (Application Service Data Unit) codes have been added, adapted to data synchronisation.