PI AF structure for OpenPCS 7 data

In the figure below there is an example of an OpenPCS 7 structure (taken from a third-party OPC UA client tool) followed by a screen-shot showing the result in PI AF.

In AF, the connector replicated the OpenPCS 7 process groups to PI AF elements and the OpenPCS 7 variables to static and dynamic PI AF attributes. The SIMATIC S7 Protocol Suite object was considered an entry to the OpenPCS 7 hierarchy.

The individual element names in the PI AF hierarchy, for instance: Connectors\PCS7\Pcs7Demo\Distillation\FIC_Feed\PID were taken from:

• Connectors – Root PI Asset Path, specified in the connector’s configuration page (Server List)

• PCS7 – hardcoded connector identifier

• Pcs7Demo – Data Source Name, specified in the connector’s configuration page (Data Source List)

• Distillation – value of the OpenPCS 7 variable #areaname

• FIC_Feed\PID – OpenPCS 7 process group

  Note: Those characters in OpenPCS 7 process group names, which cannot be used in PI, like for instance the backslash '\' or pipe '|', are replaced with underscore '_'.

Alarms and Conditions collected by the Connector

The connector replicates the OpenPCS 7 alarms and conditions to PI AF elements, PI points and Event Frames. The following section describes the applied rules and principles.

• OPC UA A&C events of the type ConditionType end-up in PI in the form of Event Frames with static and dynamic attributes; all the other OPC UA A&C events are recognized as simple alarms. For both types (conditions and alarms) the connector also builds the PI AF element structure. This structure can be divided into two categories:

  • Hierarchical (triggered alarms or conditions are positioned under that element where they originate)

  • A flat list type (a simple collection of triggered alarms or conditions)

• Hierarchical representation - the triggered alarms and conditions will be positioned in the PI AF hierarchy under that element, which represents the replica of an OpenPCS 7 object where the A&C event originates.

  

• The flat list type can be found under RootPIAssetPath\PCS7\DataSourceName\Alarms in the form of Alarms’ child elements. These child elements represent all the alarm and condition definitions, which have been instantiated (triggered) during the connector runtime. The individual child-element names reflect the value of the OpenPCS 7 SourceName attribute of a concrete alarm or condition. For conditions, moreover, the condition name is suffixed to the element name (alarms do not have names). The example below displays a condition with the name Level in OpenPCS 7:

  

  This same condition will be recorded in the PI AF hierarchy under the element: Connectors\PCS7\Pcs7Demo\Alarms as PCS7DEMO_PRJ_OS(1)::Distillation_PerformanceMonitoring/FI_BottomProduct.Level

  

• The A&C related elements the connector created thus represent all the alarm and condition definitions which have been instantiated (triggered) during the connector runtime. These elements also reference PI points where the actual values of an A&C get recorded. The name of this reference is always Message.

• For conditions, which are active for a certain amount of time, the connector also records an Event Frame. The Event Frame name consists of the condition's SourceName suffixed by the condition's Name. For example:

  PCS7DEMO_PRJ_OS(1)::Distillation_PerformanceMonitoring/FI_BottomProduct.Level

  The individual Event Frames are recorded with that many static attributes as the OpenPCS 7 WinCCAlarmConditionType defines plus the actual condition’s properties. The individual condition states get stored in a PI point, which is again referenced as the dynamic attribute Message.