Previously:

PI and MES

PI and MES: Architecture I

PI and MES: Equipment Model

 

 

The OSIsoft PI-Batch database has always conformed to the ISA 88 batch standards. It provided three mechanisms to create batch structures:

 

  1. PI Batch Generator: A Windows Service to create batches based on the batch generator in the SMT.
  2. PI Batch Interfaces: These are interface that connect to batch control system and provide automatic creation of tags, modules, aliases and batches
  3. Programmatically through the use of the PI-SDK

 

The major shortcoming of the PI-Batch Database was the lack of scalability and sole focus on batch structures.

The Event Frames Database was designed to overcome these limitation and broaden the scope of time segmentation by introducing the event concept. Now any type of manufacturing (for example discrete and batch control) can be modeled and in addition time framing such as up- or downtime, Condition Based Maintenance, Process Models, ... can be captured using the same data structure.

 

The Event Frame Database (EF) is highly flexible and can be configured for any type of event. OSIsoft provides a set of ISA 88 batch templates within the Event Frame Generator (PI-EFGEN) to build these structures. The following table shows the relationship between ISA 88 (referred as ‘Procedural Control Model’), PI Batch and EF Batch:

 

Level

ISA 88

PI Batch

EF Batch

1

Procedure

PI Batch

Procedure

2

Unit Procedure

PI Unit Batch

Unit Procedure

3

Operation

PI Sub Batch

Operation

4

Phase

PI Sub Sub Batch

Phase

5

 

….

Phase State

6

 

 

Phase Step

 

The Event Frame Templates and References are attached (see below). Similar to the Element templates, there are base templates that are derived from a universal template called ‘EventFrame Base’ and derived templates based on the corresponding base templates (e.g. EventFrame Base -> Phase Base -> Phase).

 

There are different tools to create Event Frames:

  1. Event Frame Generator: Mostly used to create Batch structures.
  2. PI Analysis: Allows to create single event frames on Element level.
  3. PI Batch Interfaces: Are transitioning from PI Batch to EF
  4. Programmatically through AF-SDK.

 

Event Frames allow to reference Elements. This mapping leads to the following simplified relationship:

 

     Procedure Model (EF) + Equipment Model (AF) = Process Functionality

 

The following shows the relationship in detail:

Batch Model.png

 

Another option is for Elements to reference Event Frames. The benefit of this design is that event frames can reference Element attributes such as Start and Stop trigger, recipe, procedure, without losing AF as the abstraction layer.

 

In summary, Event Frames provide very flexible structures for time segmentation. Using the out-of-the-box or custom templates allow fully ISA 88 compliant batch structures.

 

Next Blog:

 

PI and MES: Functional Integration (Example: Proficy Workflow)