SCADA INTRODUCTION

SCADA (Supervision Control And Data Acquisition) has been a solution for remote monitoring and control of installations of all types and sizes for decades.

The type of installation, devices and entities you want to control in a specific case usually define the specification that your system needs. As an example, controlling a water distribution system has a very different time constraint from controlling an electric distribution grid.

Size is also important… always. A power plant may have thousands of data points to address, but a singe video wall of a large energy distribution utility may be presenting to the users a million real time data points.

The evolution of communication systems was also always a big driver of SCADA solutions. Real SCADA solutions started when computers gained the capability to send and receive data via a communication channel. As the “start” was decades ago, we can imagine that the changes in say the last 40 years were not just 10 or 100 fold… We went from phone modems  that could send or receive 100 bits per second to any current household having a fiber connection doing Giga bytes in the same second.

1,000,000,000 vs 100 …

We can say that communications is the heart of SCADA, but the type of information that we want to handle has changed very little in all these years. We still talk of digital inputs, digital outputs, analog inputs or values we measure and transmit, and sometimes set points or analog outputs. This type of data can be applied or related to any field of operation, as the water and electrical systems we talked about.

SCADA applications cover many areas as utilities, industrial activities, building management , irrigation systems, home automation, in essence anything you want to be updated about and that maybe in front of you or thousands of miles away and that you need to monitor and control.

The solution that you are looking at in this website is going to address the area of small and compact solutions. The name is a small indication of the main idea of size, the metric units of measure representing 1/1000 of a unit as milli, then micro, then pico. But let’s not be fooled by the pico notion, the 40 years of technical evolution that we were talking about make the PDP11 or the first IBM PCs look like dinosaurs compared to the credit card sized Raspberry Pi single board computer that we are using as the quantum brain in this solution. 

Back to SCADA. What are then the main functions that a SCADA system has?

• Handling signals from the field:
  • binary information represented as 1 or 0, Open or Closed, On or Off
  • Measurements of any type of physical variable like temperature, humidity, voltage, current, flux, rate of change, anything that can be represented with a number.
  • Counting of events or changes of state of any digital variable
• Sending signals back to the field
  • Controls or digital outputs. These represent things as Open and Close of a device, turn ON or OFF some equipment. We can consider static controls, that remain active as long as the action is to be kept, or more often than not, we can have pulse controls, where one signal indicates “Turn ON” and another is used for “Turn OFF”
  • Setpoints or analog outputs are also used. They transmit a value that we want the field system to use for some specific function, like “set rotation value to X rpm” or “Set voltage output to Y Volt.
• Generating, manage and maintaining ALARMS. An ALARM can be defined as something that needs the attention of an operator, and that will expect some interaction with him.  These alarms are kept in lists and the “life” of an alarm has a set of states that have been used for a long time in industry, even before SCADA was there. We will address these details later.
• Data Logging. Registering and time stamping events from any origin, creating a log file that grows silently in the night and can be analyzed, exported and treated in multiple ways. More on this later as well.
• All this data has to be managed, user defined, and clearly representing the real world the system is connected to. So a major “backend” function of any SCADA is the definition and maintenance of its database. This DB will have all the definitions needed to process each signal with the exact characteristics that the user wants, bringing a huge flexibility to the SCADA application. An alarm that is presented with a text ERROR 25 is a lot worse than something like “Water tank XYZ level is too low”