RSView Supervisory Edition Installation Guide

11 • CREATING ALARMS• • • • •The acknowledge bit must be set up as a digital tag in the HMI tag database. For detailsabout setting up an acknowledge bit, see Help.Because an HMI server monitors the value of each acknowledge bit tag, using manyacknowledge bits can slow down the system considerably.Handshake bitA handshake bit is a digital tag that can be used to monitor the status of an alarm.When you set up a handshake bit for a tag, the HMI server sets the handshake bit to 1when the tag goes into alarm. If the Auto Reset feature is turned on, the HMI server setsthe handshake bit to 0 when the tag goes out of alarm.The handshake bit must be set up as a digital tag in the HMI tag database. For detailsabout setting up a handshake bit, see Help.11 • PlaceholderSwitching handshaking onBy default, handshaking is off. To switch handshaking on, do one of the following:• Use the /H parameter with the AlarmOn command.• Use the HandshakeOn command.For information about alarm and handshake commands, see Help.Alarm eventsYou can customize and extend the RSView alarm monitoring system by writing alarmdetectionalgorithms using PLC ladder logic, custom programs, or any other appropriatetools.You can then add alarm events to the RSView alarm subsystem, to respond to the alarmdetectionalgorithms for annunciation, logging, printing, and for display in alarmsummaries.By using a tag name for an alarm event, you can customize the alarm features of the tag.For example, you can use alarm events to provide a tag with more than eightthresholds.You can also use alarm events to specify an alarm’s time stamp.Since alarms are scanned in the background, alarms that occur rapidly might appear out ofsequence in RSView, because they might all be scanned at the same time, and thereforeproduce the same time stamp. If the sequence in which alarms occur is important, youmight want to record accurate time stamps for the alarms by buffering the alarms in thePLC, and then using alarm events to record them with accurate time stamps in RSView.To create an alarm event, use the AlarmEvent command. For details, see Help.11-13