Tag
- Last UpdatedApr 03, 2023
- 1 minute read
The Tag attribute (or tag name) is the name for a point. There is a one-to-one correspondence between the name of a point and the point itself. Because of this relationship, PI System documentation uses the terms "tag" and "point" interchangeably.
Follow these rules for naming PI points:
-
The name must be unique in the Data Archive.
-
The first character must be alphanumeric, the underscore (_), or the percent sign (%).
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Control characters such as line feeds or tabs are illegal.
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The following characters also are illegal: * ’ ? ; { } [ ] | \ ` '‘"“
Length
Depending on the version of the PI API and the Data Archive, this interface supports Tag attributes whose length is at most 255 or 1023 characters. The following table indicates the maximum length of this attribute for all the different combinations of PI API and Data Archive versions.
PI API |
PI Data Archive |
Maximum Length |
|---|---|---|
|
6.0.2 or later 4.370.x or later |
4.370.x or later |
1023 |
|
6.0.2 or later |
Earlier than 3.4.370.x |
255 |
|
Earlier than 1.6.0.2 |
4.370.x or later |
255 |
|
Earlier than 1.6.0.2 |
Earlier than 3.4.370.x |
255 |
If the Data Archive version is earlier than 3.4.370.x or the PI API version is earlier than 1.6.0.2, and you want to use a maximum Tag length of 1023, you need to enable the PI SDK. See ***SDK options*** for information.