Rockwell Automation FactoryTalk View Site Edition Users Guide - Manual (Page 65)

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 Which alarms will require additional actions that can be supplied using FactoryTalk
View commands.
Advantages of using FactoryTalk Alarms and Events services
There are advantages to using FactoryTalk Alarms and Events services for alarm
monitoring and control, when compared with using traditional, HMI tag alarms.
For example, FactoryTalk Alarms and Events provides a single, integrated set of alarm
information, giving applications a system-wide view and record of alarm activity, enabled
by alarm servers that support FactoryTalk services.
The decisions you make about setting up alarm monitoring and control will depend on the
design of your FactoryTalk View SE application, the types of devices the application
requires, and the processes you need to monitor for alarms.
Choosing device-based alarms
Device-based alarms are set up by programming alarm detection instructions directly into
Logix5000 controllers that support built-in alarms.
If you use device-based alarms, you only have to program alarm instructions once, in the
controller: there is no need to create alarm definitions for HMI tags.
Since alarm detection takes place in the controller, processing is faster, time stamps are
more accurate since they come from the controller, and alarm states are preserved more
reliably.
FactoryTalk View SE Clients receive device-based alarms by way of Rockwell
Automation Device Servers (RSLinx Enterprise) that are set up to support FactoryTalk
Alarms and Events. For details, see “Working with Rockwell Automation Device
Servers” on page 12-18.
Choosing tag-based alarms
Tag-based alarms are set up by specifying alarm conditions for tags in programmable
controllers (PLC-5 or SLC 500), or third-party devices communicating through OPC data
servers, that do not have built-in alarm detection.
If you want to take advantage of integrated FactoryTalk Alarms and Events services, use
tag-based alarms as an alternative to using HMI tag alarms.
FactoryTalk View SE Clients receive tag-based alarm information, by way of FactoryTalk
Tag Alarm and Event Servers that you add to a FactoryTalk View SE application.
For a list of Logix5000 controllers that support FactoryTalk Alarms and Events services, see the
FactoryTalk Alarms and Events Help.