Factorytalk Alarms And Events System; Guidelines For Logix-Based Alarm Instructions - Allen-Bradley ControlLogix 1756 Reference Manual

Guidelines for Logix-based Alarm Instructions

Guideline
Estimate increased controller memory use for each alarm. The alarm instructions use new alarm data types that contain state information and time stamps for each alarm. Estimate
Alarm instructions increase total controller scan time.
You can edit or add an alarm instruction online.

FactoryTalk Alarms and Events System

The FactoryTalk® Alarms and Events system integrates alarming between
FactoryTalk View SE applications and Logix5000 controllers by embedding an
alarming engine in Logix5000 controllers. You need the following tools:
• Logix Designer application, version 21 or later (or RSLogix 5000 software,
version 16 or later)
• FactoryTalk View SE, version 5.0 or later
• Logix5000 controllers
Firmware
ControlLogix non-redundant controllers
ControlLogix redundant controllers
CompactLogix controllers
SoftLogix controllers
Two Logix-based alarm instructions are available in relay ladder, structured text,
and function block diagram.
• The Digital Alarm (ALMD) instruction detects alarms that are based on
Boolean (true/false) conditions.
• The Analog Alarm (ALMA) instruction detects alarms that are based on
the level or rate of change of analog values.
Description
this memory use in the controller:
• 2 KB per FactoryTalk Alarms and Events subscriber that receives alarms from the controller
• There is a maximum of 16 subscribers per controller. Most applications only require one subscriber to a controller to
provide data to many FactoryTalk View SE clients.
• 2.2 KB per alarm (typical), depends on use of associated tags
The ALMD instructions and ALMA instructions affect total scan time. See Logix5000 Controllers Instruction Execution
Time and Memory Use Reference Manual, publication
An alarm state change is any event that changes the condition of the alarm, such as acknowledging or suppressing the
alarm. Minimize the potential for many alarms changing state simultaneously (alarm bursts) by creating dependencies
on related alarms. Large alarm bursts can have a significant impact on application code scan time.
Important: In redundancy systems, consider scan time impact due to crossloading alarm tag data. For more information
see the ControlLogix Enhanced Redundancy System User Manual, publication 1756-UM535.
Online edits of new and existing alarms are automatically sent to the subscribers. You do not have to re-subscribe to
receive the updated information. Online changes automatically propagate from the controller alarm structure to the rest
of the architecture.
AB Drives
Rockwell Automation Publication 1756-RM094I-EN-P - September 2015
Revision
16.20 or later
16.60 or later
16.20 or later
16.40 or later
1756-RM087 for execution times for your controller firmware.
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