A P P L I C A T I O N N O T E Annunciators as a “watcher” for your most critical processes INTRODUCTION SOLUTION DCS (distributed control system)/PLC (programmable logic controller) is the basic control element of any type of industrial control system. It may be a centralized system with one or several CPUs interconnected through a communication network. DCS/PLC systems have distributed digital and analog input networks to get informa- tion from field sensors and transmitters. Processed information is fed into digital and analog output networks to operate motors, transducers and actuators. Their CPUs have custom-made preprogrammed ladder software to process information. These software-based systems are vulnerable to cyber attacks. Most of the industrial control networks (CAN, PROFI, Control Area, Ethernet and RS485) connect to the internet or other computer networks which are not fully protected from hackers and viruses. Present day industrial DCS/PLC control systems come with redun- dancy systems to eliminate shutdowns in case of DCS/PLC hardware failures. However, this does not protect your DCS/PLC system from any type of cyber attack. Without proper protection, the safety and/or operation of your plant or business are put at great risk. PROBLEM SCADA (Supervisory Control and Data Acquisition) is custom made PC base software that can drag required information directly from a connected DCS/PLC system to be graphically displayed on a monitor screen. The latest SCADA systems come with various types of attractive graphics displays, multi screens and event data records with touch sensitive input buttons. These systems are viewed as attractive options for space saving because the entire control panel can be incorpo- rated into a single monitor screen. ADVANTAGES 1) Generates quick audible alarms for operator attention - maintains alarm state until the problem is sorted out. 2) Annunciator system is not affected by any type of cyber attack due to its standalone and software free features. 3) Comparing sensor alarms of Annunciator and DCS/PLC systems, sensor errors in either system can be identified. 4) Easy to identify active alarms displayed in a window annun- ciator in comparison to a flood of alarm messages displayed on a SCADA screen. It is very important that operators quickly respond to critical alarms. A third-party “watcher” (not another field operator) can look after abnormalities in your process. A standalone annunciator system equipped with a set of digital inputs from field sensors and lampbox outputs in the control room will work as a failsafe for DCS/PLC/SCADA systems. These isolated hardwired annunciator (or isolated software) systems can generate unmistakable alarms and audible warnings when there is an abnormality and can ultimately save your plant from a potential disaster. ...continued on back page...