SCADA - Supervisory Control and Data Acquisition

SCADA (Supervisory Control and Data Acquisition), often called HMI (Human Machine Interface), is the eyes into the plant. It supplies the operator with a graphical representation of the process they are operating. Typically, the screen has an animated process schematic. For example, motors will turn green when running or flash when faulty. With the visualisation that SCADA offers, operators can see which valves are open, what the temperature is, which motors or conveyors are operating etc. The SCADA usually includes other information from the control system, or corporate systems, such as order numbers, alarm status, recipe information, SOP (Standard Operating Procedures).

A well-designed SCADA system will not only show you what is happening (i.e. what the PLC is waiting for before taking the next action), but alert you to abnormal situations, and allow you to determine what should be happening. Many modern SCADA systems are designed using Situational Awareness. This came about because manufacturers realised that abnormal situations occurred for three main reasons: (Source: ASM Consortium)

• People and Work Context Factors: 35% - 58%
• Equipment Factors: 30% - 45%
• Process Factors: 3% - 35%

Situational Awareness attempts to remove the clutter from traditional SCADA screens. When everything is normal, the screen will look grey and boring, and when something is abnormal, it is highlighted appropriately. Operators are then naturally drawn to the abnormal situation and can take suitable action. They no longer miss important information.

SCADA systems are designed to be the eyes into the plant for real-time and short-term historical diagnostics and monitoring. Like all products, it should only be used within the design limitations. Some SCADA systems, especially ones that are not dedicated terminals, have facilities for extended functionality. Inexperienced programmers often push SCADA systems beyond their functional limits, affecting their overall functionality. Although SCADA systems have a lot of functionality, there are other solutions that achieve the extended functionality more effectively and efficiently. As an example, long-term information, or data not needed immediately for production purposes, is better to be collected into purpose-built data repositories such as a historian; it can then be analysed offline. For more information on these systems, please refer to MES.

Mescon engineers have successfully interfaced SCADA and HMI systems to several PLCs and RTUs. We have also integrated them with corporate information systems, ERPs, barcode scanners, weigh cells, databases, warehousing systems, KPIs, scoreboards, road signs and even the ‘cloud’ (web). We are certified and/or experienced in Citect, WonderWare, Ignition, Factory Talk View SE & ME, PanelView, Vijeo, Crimson, Redlion, and Omron.

Our aim is that you can use your operator interface on the plant floor with full confidence and in all scenarios.