Finding the right recipe for convergence

Development of industrial standards is not a rapid process. A standard committee will work for years to develop an industry-wide consensus on a new standard. Two committees now are actively working together, and you can imagine the extra time and effort involved. The ISA SP88 and ISA SP95 committees developing the ISA 88 Batch Control System and ISA 95 Enterprise/Control System Integration sta...


Development of industrial standards is not a rapid process. A standard committee will work for years to develop an industry-wide consensus on a new standard. Two committees now are actively working together, and you can imagine the extra time and effort involved.

The ISA SP88 and ISA SP95 committees developing the ISA 88 Batch Control System and ISA 95 Enterprise/Control System Integration standards are cooperating to make sure that they have complementary and consistent standards.

The ISA 88 standard is the defining model for batch control within the process industries. The ISA 95 standard is the defining model for Manufacturing Operations Management and MES in continuous, process, and discrete industries. The two standards have some overlap in functionality, so the two ISA committees have been collaborating to provide a consistent model.

The first result of that work is a new ISA-88/95 Technical Report: “Using ISA-88 and ISA-95 Together”. This report builds on past ISA SP88 chairman Lynn Craig's paper at the WBF North American 2005 conference. This report is free to ISA members.

The two committees have different scopes; the ISA 88 standard is focused on procedural control for the process industries, but with an understanding that the models can be applied in other types of production. The ISA 95 standard is focused on the activities covering the MES (Manufacturing Execution Systems), LIMS (Laboratory Information Management Systems), warehouse management systems, and maintenance management systems. Convergence of the standards started with the recognition that the highest level functions and data defined in the ISA 88 standard are the lowest level functions and data defined in the ISA 95 standards.

Recipe Execution, as defined in ISA 88, is the process industry terminology for ISA 95's Production Execution Management. The ISA 95 standard even includes recipe execution as an example of Production Execution Management. There is a strong equivalence between executing an ISA 88 recipe procedure and executing an ISA 95 workflow procedure. Sites that require MES functionality but also have some batch control systems are using a common pattern to integrate the systems. The MES will execute workflow procedures and some of the steps in the workflow start batches in a batch control system.

When the batch is complete, then the MES resumes its workflow and controls material movement, material tracking, and business level reporting. This model works well, because the ISA 88 batch model is concerned with how to execute a recipe, and is not concerned with how material arrives at a process cell or what happens to the material when processing is complete. The ISA 95 defines the model for movement and tracking of material between process cells and other types of work centers.

There is also additional convergence in progress. The ISA SP95 committee is developing the ISA 95 Part 4 standard, titled “Objects and Attributes for Manufacturing Operations Management Integration”. ISA 95 Part 4 will include a model for production records.

This model will be an extension to the ISA 88 Part 4 Batch Production Record models. When the ISA 88 Part 4 standard was under development there was collaboration with the ISA SP95 committee to make sure that the models could be extended to support discrete and continuous manufacturing. The ISA SP95 committee hopes to have a committee draft available by the end of 2009.

The SP95 committee is also planning to use a structure similar to the ISA 88 concept of Master Recipes and Control Recipes. Master recipes are template documents that define how to make a batch. Control recipes are copies of master recipes, with one control recipe per batch. The ISA 95 equivalents are Master Work Definitions and Control Work Definitions.

The master work definition is a template for how to perform work (which may include starting batches, moving materials, starting tests, etc..). A control work definition is a copy of a master work definition for a specific job and is used to control the workflow and material flows.

It takes a lot of time, effort, and coordination for two different standard committees to work together. The ISA SP88 and ISA SP95 committees are developing consistent standards through the dedication of their volunteer members. Their work has helped bring the benefits of both the ISA 88 and ISA 95 standards to multiple manufacturing companies.

Author Information

Michael Frayne is a Product Manager for network interfaces at Molex Inc., based in Waterloo, Ontario.

Plugging the plant security gap

There has been a battle going on in the process automation market since the U.S. government started its Homeland Security program following 9/11. As a consequence, all operators of critical and/or potentially dangerous processes and assets such waterworks, substations, oil and gas industry, chemical industries etc. had to prove that they are protected against external attacks, especially those carried out over the Internet.

During these investigations, the government learned something that those of us in the industry knew for years %%MDASSML%% software and the IP stacks implemented in today’s process control systems are extremely vulnerable. Sometimes just a short time network load of more than 10% or 20% can influence or even stop the whole process. At the moment, operators and organizations like NAMUR and NERC are putting pressure on the controller vendors requiring secure control systems.

The goal these organizations have been working on is a commonly accepted test method for industrial devices and a classification similar to the safety SIL levels. Those Security Assurance Levels (SAL) are now being defined in part 4 of the ISA 99 standard.

Since Feb 5, 2009, we have a new standard in the process industry backed by some big players and endorsed by the U.S. government and the Department of Homeland Security in particular. Implementation is causing some companies to scurry a little as there are some difficult pieces in the standard, especially for legacy systems. However there is little doubt this is how security will be handled going forward and that the big controls companies will make their process automation systems compliant with this security standard.

The big question is, will SAL certification cross over to the plant floor people who are worried about security and eventually even dovetail with SIL certifications they are having to deal with in implementing safety networks? The only reason it will not is that commercial IT standards may prevail instead!! If discrete and process diverge in how they handle security because of this it will become a pain in the butt for users and vendors who have to make sense of two very different approaches.

This will be another front in the war between IT and Automation people in the coming years. It’s too early to see who will win but it sure will be an interesting fight. It is clear to me the next few years are crucial to defining security on the plant floor.

Ed Nabrotzky is the global product manager for Molex.

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