Rockwell Automation FactoryTalk View Site Edition Users Guide - Manual (Page 313)

12 • S ETTING UP F ACTORY T ALK ALARMS
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At run time, if a FactoryTalk alarm function refers to an alarm source that becomes
unavailable, the function is evaluated but returns nothing to the expression evaluation.
For example, a device-based alarm function is not counted, if the corresponding alarm is
deleted from the Logix5000 controller, or if the RSLinx Enterprise alarm server:
 Loses its connection to the Logix5000 controller that is detecting alarms.
 Begins or is in the process of downloading a program.
 Switches from run to test program mode.
 Experiences a major or non-recoverable program fault.
 Cannot subscribe to all of the alarms at the Logix5000 controller.
If the condition causing the disconnection is resolved, the expression can be reevaluated,
with the restored alarm function included.
About controller status system alarms
When an alarm source becomes unavailable, the system generates a special type of alarm,
called a controller status alarm, in alarm and event displays and logs.
Controller status alarms provide information about the condition behind an alarm source
disconnection.
Following is an illustration of a controller status alarm in an alarm and event summary.
An expression that contains a FactoryTalk alarm function will return 0, if the alarm function
references an alarm from a disconnected controller. Provide a way for operators to monitor for
controller status alarms, so that they can confirm whether 0 is a valid expression value.