In the mid-1990s,a group of vendors convened to address the growing concern regarding connectivity to the plant floor referred to as the"Device Driver Problem."At that time,HMI and SCADA vendors were responsible for building their own driver libraries.This approach created great solutions when it included all the connectivity requirements that their end users would need,but incomplete solutions when it did not.The vendors were faced with a decision:they either needed to invest resource application-level functionality or extend connectivity.Some vendors decided to create their own Application Programming Interfaces(API) or Driver Toolkits.Although this solved their own connectivity needs,it limited end users to how they could approach purchasing additional solutions.Luckily,it was not too long before the market persuaded the vendors to collaborate and make changes that were in the end users'best interests.The initial task force consisted of half a dozen companies,including Fisher-Rosemount,Intellution,and Rockwell Software,among others.They took off their competitive hats and ventured out to solve this problem.The direction was pretty clear.All software developments at the time were targeting Microsoft Windows as the platform of choice.Microsoft's client/server technology,Object Linking and Embedding(OLE),was used to share information between applications using vendor-specified interfaces and rules.The group's initial plan was to create a solution that would generalize data transfer between applications and any data source.The result was the first OLE for Process Control(OPC) specification,referred to as OPC Data Access(OPC DA),released in 1996.
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