Rockwell Automation FactoryTalk View Machine Edition Users Guide - Manual (Page 85)

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Work with tags
This chapter provides general information about working with all kinds of tags. This
chapter describes:
 Types of tags.
 When to use data server tags.
 Steps for using data server tags.
 When to use HMI tags.
 Steps for using HMI tags.
 Browse for tags and offline tags.
 Use the Tag Browser.
 Use tags and expressions in your application.
 Log tag values.
 Use macros to assign values to tags.
For information about creating HMI tags, see Chapter 7.
Types of tags
A tag is a logical name for a variable in a device or in local memory (RAM). For example,
a tag can represent a process variable in a programmable controller.
Data server tags
FactoryTalk View conforms to the OPC DA (Data Access) 2.05a specification for
information exchange among automation or control applications, field systems or devices,
and business or office applications.
In FactoryTalk View, data servers such as RSLinx Enterprise, RSLinx Classic, and
KEPServer Enterprise provide access to OPC-DA-compliant tags. In the FactoryTalk
View documentation, the tags you use through a data server are called data server tags.
For more information about data servers, see Chapter 5.
Data server tags include tags found in Logix5000 processors and tags from other OPC-
compliant devices. You use data server tags by providing a direct reference to the tag’s
location, wherever you want your application to use the data.