SCADA system – Understanding the basics

Plant monitoring and control systems have been automated and more and more companies are moving towards it. The process data that is spread all over the plant or may even be extended in fields can now be collected and transmitted to a central control station. This allows better monitoring of processes through data integration. It is a complex activity and is performed by a number of equipments and accessories that are orchestrated to do the work. This system is what we call SCADA or the Supervisory Control and Data Acquisition. How process information is flowing through the system has to be understood correctly and it has been discussed in this post.

The working cycle

SCADA systems are available in various configurations depending on the type of application it is meant for. It comprises of a network of hardware and software components that work in unison to perform a variety of tasks.

• Data that is generated by the equipments are captured by sensors.
• It is then transmitted to remote terminal units (RTU) or PLCs (Programmable Logic Controllers).
• The information is then directed to remote computers with the help of suitable network. The information is stored in the computer for processing.
• The same computer is used to send commands to the PLCs or RTUs to instruct the units to perform certain actions.

Functions

Plants can be operated with the help of SCADA. By sending commands to the RTUs, these can be activated, like opening or closing of valves and starting and stopping motors and pumps. All information that is collected is recorded in a log that indicates about the throughput and performance. Reports are generated from the information that is gathered and these can be customized according to needs. Reports are very important to decide about the steps to be taken for better process control and performance. The system sends out an alarm whenever there are any problems encountered in the process or equipment.

There are some technical terms that are used in the SCADA system that have to be understood properly. This will enable users to comprehend the system better. Read on to know more about it.

Transducer

The transducer is the sensing element. This is extremely important as it is considered to be the eye of the process monitoring system. The function of the transducer is like a converter that converts physical quantities of pressure and temperature into quantities that can be measured electronically. The units of electronic measurements are millivolts (mV) and milliohms (mO). The pressure or temperature sensed by the pressure gauge or thermocouple is converted by the transducer.

Transmitter

The function of the transmitter that is often built in with the transducer is to convert the signals of the transducer like millivolts into milliamps that corresponds to a certain temperature. There is a set temperature range within which it operates.

PLC module

The PLC analog input module of the SCADA system has converter circuits that coverts analog signal into digital ones. Thus the binary values are obtained that forms the raw data for reports.

Hey myself Archer Finch. Even though I took extra care about my systems, but still it was more prone to hacking. With the introduction of the Scada, my system is now very much safe from all sorts of threats, as most of the SCADA system are connected to web based portals or products.

Pioneer in the industry of automation, flexible manufacturing systems, Cncs and so on, has presented his views here about Scada Free.