SCADA systems Fundamentals Industries

SCADA systems:

SCADA in automation world refers to Supervisory Control and Data Acquisition. As the name suggests SCADA role is to acquire the data from the wide area of process system and perform the control function if required. In simple SCADA master station receives the data from the remote terminals which exists in the field and takes control action if required, it also display data in the form of plots, tables, and other display modes to the operator to permits human to take the control actions. 

In modern day industrial growth process system of plant or industry spreads in wide area. There is every need to connect the process systems exists in the remote location to main control center for better control of the system and increase the reliability. Oil pipe lines laid over hundreds of kilometers are to be monitored constantly and takes control actions if required (eg: Closing or opening of valves of the pipes). Hence telemetry is often required to connect the equipment and the process systems which are separated by far distance.  Telemetry helps in receiving the information from the field locations, sends the required commands and programs. 

Hence SCADA is a combination of telemetry and data acquisition. It collects the data from the field and stores in the RTUs (Remote Terminal Units). Transfers the data from RTUs to master station on request. This received data is processed and displays to the operator on screens allowing the operator to take control actions. The required control instructions are transmitted back to the field to carryout control functions (eg: opening or closing the values)

In earlier days hard wired relay logic is used for control functions. With the advent of digital computers and electronic devices hard wired relay logics are replaced by digital electronics  incorporated in to the relay logic devices. Hence Programmable Logic Controllers are being employed in modern day SCADA