1 May 2007
We have used this space this year to study the approach, purpose, and scope of the ISO 18435 project. There are specific extensions for and standards that apply to the project.
Now we will consider a use case for integrating production, diagnostics, and maintenance information.
An activity-modeling framework similar to ISA-95 is possible for Level 2. We can model the Level 2 operations in terms of generic activities (i.e., identify, move, make, test, and fix).
These activities logically breakout into application domains, along with a set of processes, resources, and information structures, and information exchanges, to perform control, diagnostics, and maintenance functions.
In the ISO 18435 scheme, the integration of two manufacturing applications within Level 2 plays out in terms of a set of ISO 15745-process interoperability profiles that support both inter-process and intra-process flows.
Some resources are involved in both intra-process and inter-process flows, and in many cases, the same interfaces support intra-process, as well as, inter-process information exchanges.
To interoperate with all the other Level 2 applications, each application needs to offer a set of resource interfaces that reference to corresponding interoperability profiles.
Integrated applications at Level 2 have compatible interoperability profiles.
Similarly, the Level 3 activities defined in ISA-95 segment nicely into application domains, such as production, capability assessment, and maintenance.
One can model each integrated application as a set of processes with resources, such as mainframe computing units, local and wide area networks, manufacturing operations management personnel, and Level 3 software.
These resources support the intra-process and inter-process flows that are in the associated interoperability profiles. Thus, to enable each Level 3 application to interoperate with all the other Level 3 applications, a complete set of intra-process and inter-process ISO 15745 interoperability profiles can dedicate to Level 3.
The combined set of interfaces referenced in the interoperability profiles will enable production, capability assessment, and maintenance applications to be interoperable, thereby achieving the desired integration of Level 3 applications.
Applications at different levels
At Levels 3 and 2, both types of process flows occur within an integrated application or between interoperable applications. Some resources are involved in both intra-process and inter-process flows, and in many cases, the interfaces support intra-application, as well as, inter-application information exchanges.
When integrating two applications each located at different levels of an application hierarchy, the respective processes of these applications are expected to satisfy a set of inter-process interoperability profiles, some intra-level and others inter-level.
About the Author
Nicholas Sheble ([email protected]) edits the Channel Talk department. Read more about the ISO 18435 project at http://www.isa.org/intech/jan07/integration.
ISA-95 is a group of three standards that define the interfaces between enterprise activities and control activities.
ISO 18435 standard is under development. It is Industrial automation systems and integration-Diagnostics, capability assessment, and maintenance applications integration-Part 1: Overview and general requirements.