Allen-Bradley GuardLogix 5570, User Manual

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Rockwell Automation Publication 1756-UM022D-EN-P - May 2017 105
Develop Safety Applications Chapter 6
To create a safety tag, open the New Tag dialog box by right-clicking
Controller Tags or Program Tags and choose New Tag.
Figure 26 - Creating a New Tag
Tag Type
Table 30 defines the four types of tags.
Table 30 - Four Tag Types
Tag Type Description
Base tag These tags store values for use by logic within the project.
Alias tag A tag that references another tag. An alias tag can refer to another alias tag or a base tag.
An alias tag can also refer to a component of another tag by referencing a member of a
structure, an array element, or a bit within a tag or member.
IMPORTANT: Do not use alias tags between standard and safety tags in safety
applications. Instead, standard tags can be mapped to safety tags using safety tag
mapping. See
Safety Tag Mapping on page 116 .
Produced tag A tag that a controller makes available for use by other controllers. A maximum of 15
controllers can simultaneously consume (receive) the data. A produced tag sends its data
to one or more consuming tags without using logic. Produced tag data is sent at the RPI of
the consuming tag.
Consumed tag A tag that receives the data of a produced tag. The data type of the consumed tag must
match the data type of the produced tag. The requested packet interval (RPI) of the
consumed tag determines the period when the data updates.