Hello learners. Welcome to this topic on SCADA protocols. Let us try to understand about the SCADA RTU protocols and communication. Take a real-life example of a simple light control switch in a room or in a panel. There is a switch and there is a lamp fixed. Your wire connects the switch and the lamp. Here, wire transmits the power from the switch to the lamp. In the same way, the wire is equivalent to the network about what we are going to discuss. In a process, there are systems and each system need to be monitored and controlled to have a final product within the least time and rejections. Such monitoring and controlling are required to be carried out in remote sites also from a centralized control room. To enable this monitoring and controlling, we require a network, which connects decentralized control room and the remote site and transport the data. This connectivity is called the communication network. It is of a special kind. Such networks transport all the real-time data which are collected from the sensors by the PLCs RTUs. This data finally reaches the human-machine interface. In the initial days through radio, modem, or dedicated serial lines of communication of SCADA that carried out. The latest trend is to use Ethernet and IP over SONET for the SCADA data. To have effectively security control, SCADA protocols are restricted to close the local area network or LAN or wide area network or WAN. This is mainly to keep the sensitive data from the open Internet. Genuine supervisory systems do not communicate with uncomplicated electrical signals. The data of SCADA is encoded in protocol format. Earlier, SCADA systems relied on proprietary protocols, which were of closed nature. Nowadays, open protocols and protocol mediation has become the trend. This type of protocol permits SCADA connectivity between different electronics devices from different vendors, and communication between them has become possible. This demands the manufacturers to concentrate much on the design of their product, to have more compatibilities, functionalities, and capabilities. Open standard protocol usage is an important decision. As due to this, reduction in cost and maximized, the flexibility is enabled. Some of the important benefits of the open standard protocol over the proprietary are one, vendor independence, two, availability of open system connectivity, three, reliable products at optimized costs, and four, easily available knowledge and specification. Examples of open protocols include SNMP, DNP3, and Modbus. The simple electrical field devices, like sensors and control relays on their own, are not capable of generating or interbreeding communication protocols hence the need for RTU, that is, remote telemetry unit becomes necessary. RTUs interface between the field devices and the SCADA network. RTUs carry out the following functions. Connect the monitored equipment, encodes the sensor's input into protocol format, forward the same to SCADA human-machine interface. Human-machine interface between man and machine or system or device is called as HMI. Telemetry is the terminology used for the communication of information from RTU to HMI user interface. The benefits of HMI SCADA are listed here below. Situational awareness of the technicians can be improved. Technicians will have the capacity to monitor their system from anywhere at any time. Graphical representation in the form of map or picture of data information is possible if SCADA is the best. It permits users to control devices and process from remotely through its interface. Having SCADA software that supports the HMI communication protocol we have is the best way. Such protocols are Distributed Network Protocol or DNP3 and Modbus TCP/IP. As the events occur, they can be reported by RTU and the exchange of data can be asynchronous. Using a command and response protocol, data can also be exchanged. Generally, this is controlled by the SCADA master. This is called polling. Let us now look at the communication infrastructure for distribution automation. Underground fiber-optic network includes fiber optic cable, ethernet switches, fiber optic accessories. Wireless communication networks, that is GPRS, license-free radio-frequency includes, data SIM cards at Field RTU or data concentrator or meter end. Internet or MPLS connectivity at the control center end. Communication protocol between SCADA and RTU or data concentrator includes IEC 60870-5-101 which is commonly referred to as IEC-101 and IEC 60870-5-104 which is commonly referred to as IEC-104, and Distributed Network Protocol Version 3 which is called as DNP 3.0. With this, we come to the end of this topic. Thank you.
