ALARM SYSTEMS used to consist of light boxes, audible alarms, and push buttons. Only the most experienced operators could use these systems to sort out root causes of equipment failure. Remote notification of alarms was either non-existent or relegated to a single "trouble" alarm contact.
That was then. Software and hardware from HMI and PLC vendors now push alarm notification, identification, and analysis to levels undreamed of in the hard-wired world. Alarm notification has moved beyond the local level and now extends worldwide to virtually every type of networked electronic device.
Alarm messages can be sent to PCs, fax machines, pagers, phones, and personal digital assistants (PDAs), and these messages can consist of virtually any combination of text, voice, and video. Users can view and acknowledge these messages, and they also can access the control system to perform further analysis.
HMI products lead the way in sophisticated alarm notification. "With AlarmWorX32 Multimedia, users have an unprecedented set of tools to inform them of alarms and events," says Russ Agrusa, president of Iconics. "Whether the notification is via cell phone, instant messaging over the web, pop-up remote videos, e-mail, or pagers, this plug-in module makes remote notification a snap in any application."
After a user is notified of an alarm, interaction with the control system is often needed. GE Fanuc Automation's Cimplicity PalmView is a handheld PDA with a wireless Ethernet card. PalmView uses thin-client wireless Ethernet technology to present real-time machine data. The bi-directional information flow facilitated by the Ethernet card permits system interaction and allows mobile users to enter process information.
Thin-client technology used by GE Fanuc and others lets a virtually unlimited number of users receive data from and send commands to an HMI. Although many users can be linked to the main HMI, separate user licenses are not required for each remote device.
Voice recognition systems are also used in many remote alarm applications. These systems let users interact with production machinery through a series of voice commands via phones, intercom systems, and radios.
SCADAlarm is an addition to Wonderware's FactorySuite 2000 that brings remote alarm management and multimedia capabilities to InTouch--the visualization component of the suite. This enables machine operators to hear information about and to manipulate InTouch tags from any telephone.
Keeping track of who should receive what type of alarm at any given time can be a complex task. Rockwell Automation supplies its RSView32 HMI software with Messenger scheduling capabilities to help users send alarm information to the right person. Users can accommodate holidays, weekends, and business trips by pre-scheduling alarm notification destinations.
Alarm systems generate large amounts of data, and the best way for the machine operator or the machine builder with after-sales support responsibilities to manage this information is through a database. HMI vendors now include a wide range of sophisticated database tools and interfaces in their base products. Citect supplies CitectSCADA software with alarm-sorting capability.
Alarm sorting allows users to analyze alarms to find root causes, and it also lets users better manage alarms on a day-to-day basis. Alarm displays can be sorted in either ascending or descending order by one or more alarm fields without grouping restrictions. According to Citect, this is particularly useful for alarm systems involving time-stamped alarms or remote terminals where alarm events are delayed and received in batch form.
Many machine builders neither need nor can afford to pass along the costs of high-end capabilities inherent in PC-based HMI software packages. Nematron includes many basic alarm functions in its PowerView touchscreen products. Alarm or error conditions can be linked to six different pop-up windows so displays can provide instruction for alarm reaction or error correction.
Onboard displays and keypads supplied with PLCs, drives, and other controllers can be used to create very-low-cost alarm messaging systems. AutomationDirect's DL06 micro PLC can be supplied with an optional LCD that snaps onto the front of the PLC. The LCD has a two-row by 16-character backlit display with seven function keys that provide navigation through messages or menu items. The display also supports password functions for changing data-register set points.
User-defined messages can be programmed directly in the ladder logic to show important events, alarms, or faults. User-defined display messages required for alarm or monitoring purposes can be preprogrammed or imported as ASCII data from other networked devices or controllers. A user can view and make changes to data registers, monitor or force I/O points, or diagnose systems errors, all without interrupting PLC control function.