What is SCADA?

What is SCADA?

Above are some sample slides from our SCADA Basics course.

We can't assume everyone reading this "What is SCADA" blog post even knows the bare bones SCADA basics. Or even what the acronym means. So I will speak of some of the most basic SCADA principles below, the sample SCADA Basics Course PowerPoint above will give the unknowing reader a little more. If you want to learn even more about SCADA, see our new SCADA Basics Course in its entirety by downloading from http://bin95.com/scada_tutorial_siemens_automation.htm

Supervisory Control and Data Acquisition - A computer software used as operator control interface (Supervisory Control/HMI) with the ability to record data from real-world equipment it has been programmed to monitor (Data Acquisition). This SCADA software allows operators to interact with equipment and company to record data from equipment used in industries like manufacturing, process control (like oil and gas industries), infrastructure (like sewer and water, power, transportation, etc) and buildings (like security, HVAC, etc.).
Human Machine Interface - A computer software used as operator control interface (Supervisory Control) This HMI software allows operators to interact with equipment used in industries like manufacturing, process control (like oil and gas industries), infrastructure (like sewer and water, transportation, etc)and buildings (like security, HVAC, etc.).
I included the HMI definition above so you can see the similarities. For a better understanding of exactly what is SCADA. For example, if you take away the ‘Data Acquisition’ part of SCADA, what you have left is an HMI where the operator is capable of controlling multiple machines. An HMI is a software typically use for operator controls, but only one piece of equipment, one machine. It is really just semantics. Because the capabilities of this advanced HMI changed so much, the vendors gave it a new name/acronym … SCADA. Just like when the capabilities of the PLC changed so much, the vendors gave it a new name … PAC.

The real and full control of equipment is done by PLCs/PACs/RTUs/BAS. The SCADA software just gives operators a limited control decided by both the SCADA programmer and the PLC programmer. A more accurate acronym for SCADA would be 'OCADA' for 'Operator' Control and Data Acquisition. But that name choice would have hurt sales of this very expensive software. :) It could have been really shortened to "OCD" (Operator Control Data), but that would have really hurt sales. Especially since the software vendors want you to keep repeating your payment for software when you want to add more tags. (you can learn about tags/memory address names in our training course.)

One of the big features/functionality of SCADA data acquisition is for a programmer to set up alarm points and record them. The PLC/HMI commonly have alarms set too, but seldom record the history of alarms and other data due to memory limitations. As HMI software is running on a computer, it could be designed to record alarms too as there is plenty of memory, but then the vendor would call it SCADA. (So the vendor could charge you for using the memory on your computer. :)

The SCADA Basics course sampled above is from a maintenance perspective, not the operator or programmer's perspective. A maintenance person or industrial engineer may have to go into SCADA software and use predefined functions of the software to adjust or create alarm set points. Maintenance may have to do minor programming too, like adding monitoring points and operator interfaces like device graphics and operator buttons. Of course, maintenance will have to troubleshoot SCADA systems too. (The 'SCADA Systems' term as opposed to using the term "SCADA Software' is just another case of semantics.)

SCADA System
A term used to refer to a plant/city where PLCs/PACs/RTUs/BAS perform the equipment full control, but a brand of SCADA software has been interfaced with them. IE: "That pump control is not in the in the SCADA system."

What is SCADA?

I'll leave you with this thought...
What if someday 'SCADA System' evolves to a PAC using standard HTML (web page) interface so it is a onetime purchase instead of an ongoing expense, where you have unlimited expandability and any webmaster can program it for you. The purchase price, maintenance cost, and downtime cost would all be drastically reduced. (No more paying for new tags and additional memory either.) Hmmm...

Don (Follow me on Industrial Skills Training Blog and on Twitter @IndTraining .)


Popular Posts