An RTU would be a dedicated type of controller that will be designed for a very specific function, and not 're-programmable' for other uses. IE a pump controller monitoring output pressure and reservoir level, where there may be two analog inputs (pressure and level), one analog output (pump speed reference), 4 discrete inputs (local/remote switch and failsaife inputs), 4 discrete outputs (start pump, local indicators).
'SCADA = System Control And Data Acquisition' is more of a broad description of what a system will be required to do. And an HMI (simple as a selector switch panel, complex as a multi-page touchscreen display) would be one part of a SCADA which is controlling, monitoring, accepting operator inputs, collecting system data, storing data in a historian.
And SCADA usually refers to a larger, plat-wide or area-wide, system possibly comprising several PLC's and HMI.
All good info - except I'm used to SCADA being Supervisory Control and Data Acquisition...
What's in a name? Every bus, car, van or truck is in essence an automobile, it's mobile and it is doing it on itself, without being pulled or pushed. But not every automobile is a bus, or a truck or a van or a car. A lot depends on the person using the word...
Kind regards,
An RTU would be a dedicated type of controller that will be designed for a very specific function, and not 're-programmable' for other uses.
I consider an HMI or OP to be a user interface and SCADA ads to this data AcquisitionI've noticed since coming across to Canada from the UK that the Canadian engineers refer to HMI's all the time, whether they mean HMI's or SCADA. Whereas in the UK, a HMI was usually a small purpose built operator interface, like panel mate, OP70's etc and SCADA is usually a PC system with capabilities of a large database etc, like InTouch and WinCC.