Aliases Tab

Use

The Aliases tab is required in the query process only.

An alias enables the selection of certain tags and groups them. These tags constitute a subset of the tags provided by the data source. This improves system performance since only the values of the selected tags are queried by the source system. See also: Filter Functions.

However, you can use the alias to rename the tags so that, for example, you can display shorter or more descriptive tag names in the destination system.

Integration

You can assign one alias only per agent instance. You assign the alias to the agent instance on the Tag Query tab. See also: Tag Query Tab

Activities

1. To create an alias, select your source system and then click on the Aliases tab.

2. On the Aliases tab, choose the Add Alias pushbutton.

   The Alias Configuration dialog box appears.

3. In the Alias Configuration dialog box, choose Browse for Tags to search through all the data in the namespace of the source system, for example, the OPC server.

   PCo then displays the Browse Information dialog box.

4. In the Browse Information dialog box, you can enter the following:

   • In the Mask field, you can restrict the selection of tags by entering, for example, Int*. In this case, only the tags whose names begin with Int are selected from the source system.

   • You can have an alias generated automatically by the system if you select the Generate Alias checkbox. The system then displays the complete namespace. However, this approach is useful in exceptional cases only, for example, if you want to rename all tags.

   • Another option is to select the Browse Secondary checkbox.

     If you select this checkbox, PCo gets the available additional information (such as the quality of a measured value or the timestamp of the value generation) for each tag.

5. Choose OK in the Browse Information dialog box.

   The namespace of the source system is now searched.

6. PCo displays the namespace of the source system in the right-hand half of the screen.

7. To be able to display the entire hierarchy of the namespace, open the top node (Address Root) in the right-hand half of the screen and then all lower-level nodes.

8. Click to choose the tag or tags that you want. Use drag and drop to drag the tag or tags over to the Root node in the left screen area, as shown in the example:

   

9. If you want to display the details for the selected tag, click on the selected tag and choose the Hide/Show pushbutton.

   In the Details screen area, the system then displays all information for the tag:

   • The information about the selected tag is displayed on the Tag tab:

     • Name of the tag

     • Data type of the tag

   • Metadata tab

     Metadata is additional data for a tag that describes the properties of the tag. The metadata remains constant; for example, the description of the tag, the minimum or maximum value defined for the tag. The name, the value, and the data type are always displayed for each of the metadata.

   • Secondaries tab

     The secondaries for a tag are only displayed if you have previously selected the Browse Secondary checkbox.

10. Choose the Close button to save the selected tag(s).

Example

Using the query process, you want to check the temperature (tag 1) and pressure (tag 2) of a boiler on a regular basis. The source system supplies numerous different tags. On the Aliases tab, you can now group the two tags under an alias for the boiler.