Usually SCADA and HMI are the control systems that are applied in any organization. SCADA is stand for Supervisory Control and Data Acquisition, this is the higher level system that supply the summary of control and processing of the data for a bigger area in the plant or for the whole plant. Usually SCADA gives more historical type and overview data and generally has more move ahead on the functionality.
HMI is stand for Human Machine Interface, this is usually at the machine level categorized as a graphical user interface, which offers control and data visualization for a single machine in small area or plant, and is mostly always assembled on or near the machine. An HMI generally offers basic data visualization and low level control, from displays of text only to the graphical displays.
SCADA is usually implementing when the control system and sensing involves large distances (it may reach in kilometers). Typically there is local control at each RTU and a very small quantity of control from the system of main control (usually called as HMI). HMI is principally element of all systems, whatever the distances are large or small.
According to the software, SCADA is a software package which can be installed in PC to make user identified program. While the HMI is an electronic module with pre-installed program, it can be editable and control the buttons. But HMI and SCADA are doing the similar functions. HMI and SCADA refer to a system which saves the data from a variety of field devices to monitor and control the variables of process.
The infrastructure and industrial processes are usually controlled by the computers. SCADA has the applications program in power generation, manufacturing, refining, production and many other economy sectors and for process control and monitoring can be discrete or continuous, as per the requirement needed. SCADA is also used even in the facility processes of installations such as port, airports, railway stations and space stations to monitor and control a variety of processes.
HMI previously recognized as MMI and is still applied is stand for Man Machine Interface. These packages generally integrate software applications and hardware and are applied as an interface between an operator and a process control or a machine. You can think of a HMI as a graphical interface to a Programmable Logic Controller (PLC) or other process control. A control of touch screen, which lets the operator to utilize the computer screen or other types of displays to switch things on and off and locate parameters as well as analysis fault routine is a good sample of HMI.
For the process control, SCADA is a software application program category for the process control and therefore also as an HMI-system. In the other hand, HMI systems consist of not only SCADA, but also local panels with the lamps and push-buttons.
SCADA is a very large term in nowadays process control arena. There are a lot of programs SCADA in the market. A program SCADA will let you to incorporate horizontally across the management information systems and the plant floor. One of the best programs SCADA on the market nowadays is called as Wonderware. Minimum they show off of the largest market share. Others manufacturers are Allen Bradley's RS View, Intellusions, IBM's Plant Floor, and others.
Summary of this differences between SCADA and HMI
• SCADA defined as supervisory monitoring and control in the plant, and HMI is a division of SCADA.
• HMI is stand for Human Machine Interface, it links with all the processes and then display or show this data to the operator.
• The HMI function as well as required is critical for the good operating SCADA.