SCADA Software consists of several basic modules or components. The most essential module is the I/O module which is meant to communicate with various devices, or otherwise the system would not be called SCADA. The secondary component is mimic module, then the third one is Alarm module, Trending, Reporting. And usually a typical SCADA software would need Tag System to share data across all component or get them connected, and lastly the program backbone would powered by a Script/Logic control in order to get them working together with correct sequence and proper order.
On top of basic components, a decent modern SCADA software would further equipped with advanced modules like Redundancy, Scheduler, Recipe, User Management, Internet access with high security implementation.
I/O driver is meant for SCADA software to communicate with external devices or equipments via its associated communication protocol. This is the most essential feature of a SCADA system. Two of the mostly used communication protocols are Modbus and OPC, due to its legacy and wide support.
The control or changing of equipment parameter will be done through this driver, and the status and parameter reading will also be done via the similar channel. This reading and writing of data compliment the 4 letters of “Control And Data Acquisition” in SCADA acronym. That’s why this I/O module is the most essential part of SCADA system.
The SCADA software is mostly hooked up to the equipment via serial link in RS232/RS485/RS422 before year 2000, but it’s now usually being connected using ordinary computer network either through Ethernet cable or wirelessly connected.
Mimic Screen Animation
As the name suggests, Mimic Screen is to imitate the physical look of the devices or equipment on the screen. However, it is meaningless if the mimic is just imitate the physical object into the screen, so usually the status of the equipment will also be reflected on the screen itself, whereby we call this process as animation. The simplest animation is color changes representing different status according to specific legend, for instance, Stop status as red, Run status as green. More lively animation would be rotating, or movement for equipment state indication. For example a rotating agitator, a level indication, a moving conveyor and etc.
On top of data and status reading, mimic screen also allows user to control the linked up equipment, so that starting or stopping of a system can be done through mouse click. The beauty of Mimic Screen is to allow operator to have the overview of the plant floor without needing them to go to the site to check out the condition, as well as controlling the devices without any physical access.
Alarm annunciation is not essential to SCADA but play a very critical role during operation. Because it allows operator to be informed and take necessary action when any of the operating parameter is beyond acceptable limit, or any unwanted event has occur. A traditional presentation of alarm is through alarm viewer, whereby alarm will be displayed according to timestamp, or sorted under its severity, or any other preferences like grouping. Traditionally, the alarm will be logged and printed using dot matrix printer, this is still being practiced in conservative industries and facilities owner in the believe that even when power failure or database get corrupted or interfered, the previously logged alarm will still can be traced. However, modern alarm management would opt to have different path of output, on top of internal database storage, the alarm can also be sent out to individual recipients via email or SMS. This way, the traceability of the alarm or event will still be available in the case of main SCADA system failure.
Trending is not essential in all cases but can be equally important when come to analysis or troubleshooting of problem. Some system split trending into Real-time and Historical but they are serving the same purpose, they are chosen parameters being trended over time. Trending allows analytic to be performed on a collection of data, it can be used for preventive maintenance, or some troubleshooting can be traced back after certain incidence occurred.
Reporting is important to production and analytical oriented application. Report generation in SCADA is not any different than other application. The real-time data is stored and tabulated according to required format, some pie/bar chartings can be added as needed. And then it can be printed to a printer, or simply generate into PDF as soft copy.
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