PI System Analysis Triggers: Incorporating EMDVB Attributes in Templates

In the realm of PI System analysis, configuring triggers on specific attributes can sometimes lead to head-scratching scenarios, especially in cases involving dynamically created attributes from interfaces such as EMDVB (Event Message Driven VB). Here, we explore a common issue and provide insights into how to effectively manage analysis triggers when working with EMDVB attributes alongside PI Tags defined in element templates.

Understanding the Challenge

Consider a typical analysis scenario where a user has an analysis defined on a PI AF element template that utilizes four PI Tags as inputs. While three of these tags are firmly rooted in the element template, the fourth, let’s call it BatchID, is dynamically created and populated by an EMDVB interface. The challenge arises when an attempt is made to configure the analysis to trigger specifically on the EMDVB-generated attribute, BatchID. However, the “trigger on” configuration fails to list BatchID as an option.

The reason for this is rooted in the nature of template configuration: analysis triggers can only be set on attributes explicitly defined within the template context. Since BatchID is an alias attribute generated by EMDVB and not initially part of the template, it remains invisible in the “trigger on” list.

The Key Solution

To resolve this conundrum, the attribute BatchID needs to be explicitly added to the template. This inclusion allows the attribute to be recognized within the template’s context, making it available as a trigger option.

Steps to Add EMDVB Attributes to a Template:

1. Evaluate Template Needs: Confirm that all instances of this template require the BatchID attribute for triggering analyses.
2. Modify Template: Add a placeholder for the BatchID attribute within the element template.
3. Consider Default Configuration: Configure any necessary default settings or descriptions for clarity.
4. Check for Conflicts: Ensure that adding this static definition does not interfere with EMDVB’s functionality in terms of writing data.

Addressing the Concerns

A point of contention often arises about whether this addition impacts EMDVB's writing operations, or if it could potentially lead to duplicated attributes. Here’s what to consider:

• Writing Values: Adding BatchID to the template should not impede EMDVB's ability to write values unless the attribute reference path is significantly altered.
• Duplication: Properly added, the BatchID attribute should leverage the same tag and avoid duplication, as long as naming conventions are consistent and the existing EMDVB logic automatically aligns with AF configurations.

Conclusion

Incorporating dynamically created attributes like those from EMDVB into PI AF templates simplifies the management of analysis triggers and enhances flexibility in analysis configuration. By ensuring that all necessary attributes are well-defined in templates, users can maintain robust trigger configurations and avert potential pitfalls in automated data processes. Always ensure to align templates with both operational needs and interface configurations for seamless integration.