“It’s web services up and OPC down.” Yokogawa systems architect Dave Emerson explained where the company’s new MDX integration platform fits between process automation and enterprise systems. |
Emerson, in his address on business and control system integration this week at the Yokogawa Users Conference, indicated that the standards-based approach Yokogawa takes—using the ISA88 and ISA95 toolsets he helped to pioneer—actually lowers the total cost of ownership (TCO), provides real economies of scale, removes costs from the supply chain and enables true interoperability.
“Adoption of these standards is key!” he said.
In the bad old days, there were point-to-point interfaces that were brittle and broke down frequently. The introduction of OPC went a long way to removing those costs from the supply chain. “Here’s a way that standards can make life easier,” Emerson said.
“Eighty percent of process companies use SAP,” he went on, “That’s over 14,000 manufacturing sites. Yet fewer than 7% fully integrate manufacturing floor information to SAP. Something is wrong with this picture.”
Arla Foods has spoken before of the difficulties it faced in interfacing disparate systems in multiple plants to SAP. “This is the same problem we faced pre-OPC,” Emerson pointed out, “Just at a higher level.”
Arla Foods found that a standards-based normalized data exchange format made it much easier to connect to SAP. According to Emerson, they used the ISA99/WBF tool, B2MML/XML, to do the exchange. Business-to-Manufacturing Markup Language is an XML schema implementation of ISA95 written by a team from WBF led by Dennis Brandl and Emerson. In fact, Emerson noted, SAP now has native B2MML support.
Why should manufacturing enterprises use ISA95? It provides a framework for integration projects and separates business processes from manufacturing processes.
The focus of ISA95 is on functions, not systems, organizations or individuals. “It is an open standard with wide adoption,” Emerson noted. And there are protections to make sure each application remains in its own domain. “We don’t want the ERP system to be opening valves, or the DCS writing checks,” Emerson said.
The current best practices in enterprise integration use standards-based data formats and web services, Emerson claimed. Why? “They are current, supported by Microsoft, safer, more secure than DCOM and completely understood by IT,” Emerson said. “It is a lot easier to get IT to do stuff they understand.”
“And now for the commercial,” Emerson said, as he introduced Yokogawa’s MDX manufacturing data exchange. “We don’t like to call this space MES anymore,” Emerson said, “Because it has lots of baggage. So we call it MOM, manufacturing operations management. MDX is in the manufacturing operations domain.”
Fundamentally, Emerson argued for a simplified model where MDX sits between the OPC servers and the process automation system and the ERP system. Of course, MDX is web-services-based, is extensible and has built-in support for SAP, ISA95/B2MML and OPC. “It is web services up and OPC down,” Emerson added. “And don’t be surprised to see a trend where web services migrate downward, maybe even to the field device level.”
Yokogawa worked closely with SAP to develop a range of SAP interface solutions and has received NetWeaver certification. Every company’s SAP integration is unique, though. So Yokogawa has designed a “baseline SAP interface” to act as a template for customization.
Emerson reiterated that standards-based integration offers the best opportunity for the lowest TCO. He urged the audience to take a good look at MDX for standards and web- services-based integration, and suggested using the SAP baseline tool for specifying integration requirements.
