SCADA Communication Protocols: Modbus & IEC 60870 – 5

Supervisory Control and Data Acquisition (SCADA) systems are the basic components of monitoring and controlling important infrastructure, such as power, communications, transportation, pipelines, chemicals and production plants. Two of the most often used protocols in SCADA networks are Modbus and IEC 60870 - 5. A communication protocol is a collection of rules that enable two or more networked entities to interact with each other. Both the transmitter and the recipient of the information must agree on the protocol. Modbus is an open-source protocol that is used by 80 - 90% of plant equipment (inverters, trackers, and so on). These communication protocols are discussed, along with a description of their functions. These protocols are compared in terms of architecture, operations carried out at different levels, device referencing (addressing), and configurable settings. This paper gives the comparison of protocols and the choosing of protocol depends mostly on application.