The Role of Programmable Logic Controllers in a SCADA System

In industrial plants that deal with water, wastewater, oil & gas, the technology used to monitor is complicated and important. Without the right technology in place, these industries would fail to provide the essential services that people rely on for normal living. Among the two most important technologies in the modern industrial landscape are SCADA and PLC. While some people seem to think these two things are in competition, the fact is that these distinct technologies work hand in hand to provide key service.

What is a PLC?

When you are trying to figure out what is a PLC, you should know that it is a piece of hardware. PLC stands for programmable logic controller. A programmable logic controller is installed to monitor sensors. In this manner, a PLC stands for data collection, receiving critical information about the flow and input within the system. To this end, the PLC will also perform basic interventions, triggering outputs when the parameters programmed into the system are met. A PLC is a versatile piece of equipment, which holds up under harsh conditions with advanced options for programming and real-time usage.

Specifically, PLCs control some of the most complex processes within industrial plants. They are often deployed to monitor running machines and motors. In order to provide more functionality, a PLC is easy to program. Moreover, these devices are scalable. This means they can fit a wide range of requirements depending on the operation in question. The PLC was developed as an upgrade over the relays and timers that used to be common on industrial machinery. Modern PLCs offer far more complexity to the monitoring and are increasingly dynamic with the information they provide.

What is SCADA?

SCADA stands for Supervisory Control and Data Acquisition. SCADA is a monitoring software used in these industries. As software, it helps control the hardware and makes a record of the data collected from all remote locations. SCADA software is connected to computers, graphical user interfaces, sensors and networked data communications in order to provide a broad picture of the process. Within this context, management teams in these industries rely on SCADA to monitor progress and make operating corrections throughout the plant.

Because SCADA is a central system, it is usually installed on a computer in a monitoring hub at a plant. In order to provide the necessary data, SCADA works with a variety of other systems. It serves as an interface of sorts, bringing various plant data together for assessment purposes. From this information, the operator can enter changes as necessary through the SCADA interface in order to control the flow and operation of the working parts within the plant.

What is the Difference Between PLC and SCADA?

When comparing SCADA vs. PLC, it is important to start with the basics. At the core, the difference between a programmable logic controller and SCADA comes down to the type of technology. A PLC is a piece of physical hardware. SCADA, on the other hand, is software. To this end, a PLC is physical. You can hold a PLC and examine it. As software, SCADA operates on a computer system and can be compared to an operating system like Windows.

With this comparison, SCADA has a much wider purview. This software is designed to control the entirety of the system, collecting data from all inputs and monitoring all devices. A PLC, by contrast, focuses on one element of the system.

What is the Relationship Between PLC and SCADA?

With these differences, it might be easy to assume that there is no PLC SCADA connection. However, the relationship between PLC and SCADA is very important. Both PLCs and SCADA software are used in the same industrial context within processing plants. This means that these technologies are essentially partners for safe and efficient plant operation. SCADA can be looked at as the broad software structure that supports the system. PLCs are a part of the system that SCADA oversees. The PLCs need SCADA to control their function, but SCADA relies on data from the PLCs to complete its overview.

This PLC SCADA relationship is invariably powerful in creating an automated system to accurately prescribe maintenance tasks. For example, if used to monitor a turbine, the PLC may collect data that suggests there is too much vibration in the system. The PLC will transmit that data back to the SCADA software. SCADA will analyze the readouts and determine whether or not an adjustment needs to be made to the system. If a change must be made, SCADA transmits the changes back through the PLCs to facilitate the correction.

Clearly, it is not a question of SCADA vs. PLC. Instead, it is a honed technological partnership. By understanding the function of both systems, it is easy to see how they work together for superior performance in industrial contexts. To learn more about SCADA software or PLCs connect with us at High Tide Technologies.