When integrating or better merging OSIsoft PI with a MES application there are typically two options being used:
- PI-SDK or AF-SDK solutions for NET based MES systems
- ODBC/JDBC both requiring PI OLEDB Enterprise & PI SQL Data Access Server for NET or Java based applications
Both options require support from the MES software as well to allow for mapping, data access and events.
Proficy Workflow is a good candidate for integration since it provides well documented SDK’s for 3rd party vendors to expand and enhance the core system. This is mostly accomplished by custom WCF services that are called from the workflow application.
Note: Proficy Workflow is not the only MES software that is based on NET and provides integration support. This is just an example and shows the general concept.
Proficy Workflow already has a connector for read and write access to PI tags. In this use case the MES application contains all the business logic, aggregation and analytic and the PI system is simply used as another data repository comparable to an OPC interface.
A better way is to merge the two application to achieve synergies and maximize the benefits of both. The following shows a much tighter integration of both systems:
As an ISA 95 compliant workflow engine Proficy uses the following resource models
and production models
Work Process Segments
Work Definition Segments
The equipment model is the only data model that it shares with the PI system. Out of the box Proficy MES does not support batch or the more generic event frames.
Therefor to fully utilize PI from MES requires the development of the following interfaces:
- Synchronizing the Equipment Model: Even though both data structure are ISA 95 compliant, the table structures are different and therefore require mapping.
- AF Data access and events: Events can be used to trigger workflows that provide actions based on for example a calculation. An example would be the creation of a maintenance order based on runtime conditions (e.g. Condition Based Maintenance). This interface should be bi-directional so MES data can also be processed in PI.
- EF Data access and events: To fully utilize the batch capabilities of PI requires the MES system to process new batch information. The batch completion event could for example trigger quality control workflows or workflows that communicate resource balances to the ERP system.
Another example would be OEE events such as Planned Downtime or Breakdowns that are captured in PI and reviewed/processed in MES.
The main benefit of this integration type is that data analytic in PI is not happening in an isolated environment and that the results can be used to trigger business transactions. The benefit from the MES perspective is a much more granular data access, aggregation and overall that Engineering and Business will be looking at the same set of data.
The drawback is that an approach like this will require some customization. As mentioned earlier some of the risks can be mitigated by choosing a MES system that already offers well document interfaces. Also it is important to standardize the data models. ISA 88 and ISA 95 might be restrictive in the implementation but do have the benefits that the subsequent integration is seamless.
In the upcoming blogs I will show the three interfaces, some code examples and applications.