Alarms

Use alarms to notify users of conditions that they might need to respond to, such as temperature over-limit, excessive current, or a motor failure.
Logix Designer
 supports the following types of alarms:
  • Instruction-based analog alarms.
    An analog alarm defines a condition that evaluates a single analog tag against up to four limit values (high-high, hi, low, and low-low) and up to two rate of change limits (positive and negative). Use the ALMA instruction to implement this type of alarm.
  • Instruction-based digital alarms.
    A digital alarm monitors a tag for alarm conditions based on whether the tag is equal or not equal to zero. Each value represent a specific alarm condition. Use the ALMD instruction to implement this type of alarm.
  • Tag-based alarms and alarm definitions.
    A tag-based alarm is similar to a digital alarm in that it monitors a tag value to determine the alarm condition. However, a tag-based alarm is not part of the logic program and does not increase the scan time for a project. Use the
    New Alarm
     dialog box to implement a tag-based alarm.
    An alarm definition is associated with an Add-On Instruction (AOI) or a defined data type. When a tag is created using a data type or an AOI that has alarm definitions, alarms are created automatically based on the alarm definitions.
    TIP:
    Tag-based alarms are supported only on
    Compact GuardLogix
     5380,
    CompactLogix
     5380,
    CompactLogix
     5480,
    ControlLogix
     5580, and
    GuardLogix
     5580 controllers
    .
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