RSView Supervisory Edition Installation Guide

11 • CREATING ALARMS• • • • •Alarm functions in expressionsWhen a tag goes into alarm, or an alarm event occurs, certain information about the alarmis recorded in the value table together with the value of the tag or alarm event. Usingexpressions, information about alarms can be retrieved on a tag-by-tag basis. Forinformation about alarm events, see page 11-13.Checking for tags in alarmIf the system detects that a tag is in alarm, it sets an internal alarm bit, and then resets thebit when the tag is out of alarm. The following expression checks if a tag is in alarm:11 • PlaceholderALM_IN_ALARM (tag)where tag is the name of the tag you want to check for alarms. When a tag is in alarm, theexpression result is 1. When a tag is out of alarm, the expression result is 0.One way to use this expression is to animate the visibility of a graphic object in a display.When the tag goes into alarm, the ALM_IN_ALARM expression is set to 1, making theobject visible. This is an effective way to draw the operator’s attention to the alarm.Checking for acknowledged alarmsThe following expression checks if an alarm has ever been acknowledged:ALM_ACK (tag)The expression ALM_ACK returns 1 if an alarm has been acknowledged. If a tag goesout of alarm without being acknowledged, the expression returns 0.When alarm monitoring starts and a tag has never been in alarm, the ALM_ACKexpression returns 1 by default. To reverse this default behavior, create the registry keyAlarm Initially Acked on the computer running the HMI server. Once you have createdthe key, change its string value to False. The key is located at:HKEY_LOCAL_MACHINE\Software\Rockwell Software\RSView Enterprise\Alarm ServerTo create or change the key, use the Windows ® Regedit32 utility. For details about usingRegedit32, click Help in the Registry editor window.ALM_ALLACKED (tag*)The expression ALM_ALLACKED (tag*) returns 1 if all tags that match the patternhave been acknowledged. If any of the tags have not been acknowledged, the expressionreturns 0.11-11