PLC vs SCADA - Difference between PLC and SCADA

 PLC vs SCADA - Difference between PLC and SCADA

PLC is a Hardware to read the sensor and solve the algorithm and gives the controlled output. Whereas Scada is the software which can be interfaced to PLC, to read and present the information in graphical, animated form or make log.

A PLC, Programmable Logic Controller, reads inputs, executes logic, and writes to outputs.

A SCADA, Supervisory Control and Data Acquisition connects to a group of PLC's and provides remote monitoring, control, and alarming.

A DCS, distributed control system, has both SCADA and PLC functionality. The PLCs are sometimes called RIO or RTU units often run proprietary or application-specific code, such as a rolling mill DCS.

SCADA can then connect to a DCS using drivers such as Kepware Technologies to integrate the DCS system with other applications across your plant/enterprise.

As you have previously learned, a SCADA system is a collection of both software and hardware components that allow supervision and control of plants, both locally and remotely.

A DCS is also a collection of components used for the same purpose.

A SCADA system is used to gather and present data to operators, make decisions about processes with the aid of operator input, and control plant functions based on those decisions.

The DCS’s role in plant automation is the same as the SCADA system.

Human Machine Interface (HMI) panels are the primary graphical interface between the plant processors and processes and the operators interacting with and controlling those processes.

The HMI panels can be procured from the same manufacturer as the controller, such as Siemens, Allen Bradley, GE, and Schneider Electric, all of which produce their brand of HMI panels.

There are also independent HMI panel manufacturers such as Red Lion.

While most of the manufacturers may have their own brand of HMI, typically, additional software is needed to program the HMI.

In the case of Siemens, WinCC software, Allen Bradley requires FactoryTalk View, Schneider needs Vijeo Designer or Citect, and so on.

There may be some PLC/HMI programming software that is integrated for the manufacturer but for the most part, they are separate software packages requiring separate purchases.

Having the same vendor of PLC and HMI may seem to be an advantage but as noted, the requirement for additional software is definitely not beneficial.

HMIs are primarily used in small scale automation environments. When you have larger-scale systems, the interface with the plant process is typically a desktop computer.

This computer requires its own software package such as Intelllution or iFix, Wonderware, or VtSCADA to name a few.

While a SCADA system has HMIs or computers that are not necessarily from the same manufacturer, the DCSs have graphical interfaces that are typically integrated within the DCS system.

Now let’s discuss the brains of the operation.

Within the SCADA system, there may be PLCs and RTUs. As you are aware by now, these components require programming in order to execute commands essential to plant operations.

Communications within a SCADA system can vary widely and have adapted to the changing technologies while the DCS has also adapted, there are still some proprietary communications that can be challenging.

There are not massive differences in the systems.

DCSs have integrated operator interface software with tag databases, while SCADA requires you to purchase additional software and build or import your tags.

If you have a very time-sensitive process, SCADA systems may have a slight advantage as the processing time is faster.

 PLC vs SCADA - Difference between PLC and SCADA

PLC is a Hardware to read the sensor and solve the algorithm and gives the controlled output. Whereas Scada is the software which can be interfaced to PLC, to read and present the information in graphical, animated form or make log.

A PLC, Programmable Logic Controller, reads inputs, executes logic, and writes to outputs.

A SCADA, Supervisory Control and Data Acquisition connects to a group of PLC's and provides remote monitoring, control, and alarming.

A DCS, distributed control system, has both SCADA and PLC functionality. The PLCs are sometimes called RIO or RTU units often run proprietary or application-specific code, such as a rolling mill DCS.

SCADA can then connect to a DCS using drivers such as Kepware Technologies to integrate the DCS system with other applications across your plant/enterprise.

As you have previously learned, a SCADA system is a collection of both software and hardware components that allow supervision and control of plants, both locally and remotely.

A DCS is also a collection of components used for the same purpose.

A SCADA system is used to gather and present data to operators, make decisions about processes with the aid of operator input, and control plant functions based on those decisions.

The DCS’s role in plant automation is the same as the SCADA system.

Human Machine Interface (HMI) panels are the primary graphical interface between the plant processors and processes and the operators interacting with and controlling those processes.

The HMI panels can be procured from the same manufacturer as the controller, such as Siemens, Allen Bradley, GE, and Schneider Electric, all of which produce their brand of HMI panels.

There are also independent HMI panel manufacturers such as Red Lion.

While most of the manufacturers may have their own brand of HMI, typically, additional software is needed to program the HMI.

In the case of Siemens, WinCC software, Allen Bradley requires FactoryTalk View, Schneider needs Vijeo Designer or Citect, and so on.

There may be some PLC/HMI programming software that is integrated for the manufacturer but for the most part, they are separate software packages requiring separate purchases.

Having the same vendor of PLC and HMI may seem to be an advantage but as noted, the requirement for additional software is definitely not beneficial.

HMIs are primarily used in small scale automation environments. When you have larger-scale systems, the interface with the plant process is typically a desktop computer.

This computer requires its own software package such as Intelllution or iFix, Wonderware, or VtSCADA to name a few.

While a SCADA system has HMIs or computers that are not necessarily from the same manufacturer, the DCSs have graphical interfaces that are typically integrated within the DCS system.

Now let’s discuss the brains of the operation.

Within the SCADA system, there may be PLCs and RTUs. As you are aware by now, these components require programming in order to execute commands essential to plant operations.

Communications within a SCADA system can vary widely and have adapted to the changing technologies while the DCS has also adapted, there are still some proprietary communications that can be challenging.

There are not massive differences in the systems.

DCSs have integrated operator interface software with tag databases, while SCADA requires you to purchase additional software and build or import your tags.

If you have a very time-sensitive process, SCADA systems may have a slight advantage as the processing time is faster.