- May 26, 2011
Automation.com, May 2011
By Roy Kok
Over the years, we‚Äôve had sensor upgrades, improved controllers, better operator visibility, data archiving and analytics, and now we have enterprise integration for improved material management, corporate agility, regulatory compliance and a host of other features.
By Roy Kok
Over the years, we’ve had sensor upgrades for process measurement, improved controllers for automation, HMI/SCADA installations for Operator visibility, Historians for data archiving and operational analytics, and now we have enterprise integration for improved material management, corporate agility, regulatory compliance and a host of other features. The manager makes the decision, and the engineer is saddled with a lot of work and stress. That work often rolls downhill, creating opportunity for System Integrators. We are all in an age where there is a technology abundance, leading to many ways to skin the cat. Have you researched all the alternatives? Are you up to speed with the latest tools to solve complicated enterprise integration?
What does integration mean to you? It may mean sending data to your corporate database, enabling tools from Oracle, SAP and other enterprise vendors to report and analyze on it. The first step is usually to create an enterprise dashboard of KPIs (Key Performance Indicators). That should keep management happy for a while. But then, the focus will shift to even tighter integration. You’ll want to close the loop on equipment, enabling data to flow from the enterprise back down to the equipment. How you accomplish all this is very much driven by your automation perspective. Will you control this from the Enterprise, or will you coordinate this from the plant floor.
Traditional Thinking about Data Collection
Traditional approaches have tended to put higher intelligence in layered systems, after all, they are typically leveraging high power computers, and have access to a broader range on information through networks. So, the PLC is controlled by an HMI or SCADA and the SCADA is linked to another Supervisory system and to a Historian and we install “Integration” solutions to tie it all together. As we layer these solutions, the maintenance is increased (maintenance of more sophisticated software, operating systems, etc.) With the abundance of development tools and smart engineers, custom software is often the solution to integration. With custom software comes a higher long term cost of ownership, driven by the higher complexity, increased troubleshooting, feature creep and the cost of developing systems with “Tribal Knowledge”, needing a domain expert to manage it going forward. Some think of this as Job Security… Managers are beginning to know better. The best solution is always the standard product, purpose built for the job and tested in countless similar applications. The days of custom solutions are coming to an end.
The traditional approach requires systems to talk down to the process, polling them for status, pulling data for enterprise purposes. This may seem the logical approach from a higher level system perspective, but there are drawbacks… Polling for information can create significant network traffic. You may be looking for the conclusion of a process, and for performance sake you’ve set the poll time high in order to deliver a quick turnaround. In the meantime, you are using automation network bandwidth (usually a precious resource).
Consider a PLC Centric Approach
The PLC (Programmable Logic Controller) is the brain of your automation system. Why not give it the intelligence to interact with enterprise systems? The PLC knows when the data is available. It can assemble the needed data into a clean and efficient transaction, delivering exactly what the enterprise system wants, without any polling. In addition, the PLC knows the status of the process, and can know when additional information is needed. Why not let the PLC be in control of Enterprise System interaction?
Putting the PLC in charge is exactly the approach being taken in many of today’s leading automation solutions and the products exist today to make it happen, elegantly, efficiently, reliably and affordably.
Enterprise Integration can be accomplished through two methods. The most common technique is to use COTS (Commercial off the Shelf) products such as a Communications Driver, Data-Logger and Custom Developed Glue software to integrate the solution on a personal computer platform. Again, this solution will require the polling of process equipment to ascertain status and affect appropriate data transfers. A newer solution revolves around the use of an “Integration Appliance,” that can be inserted into a PLC Rack, with backplane coupling for optimized performance. This second approach leverages technology specifically developed for the purpose of Enterprise Integration. The Appliance, with preloaded application software, is a COTS device that is simply configured for the task at hand. The configuration resides in Flash Memory that can easily be transferred to a backup device, should Murphy strike. (See past article)
OLDI’s eATM (Enterprise Appliance Transaction Module)
Configuring Data Uploads to your Enterprise Databases
The key to acquiring data from the plant floor and sending it to an enterprise system is to aggregate the right data, at the right time, and transfer the data as reliably as possible. Collecting the right data means coordination with equipment operations, or operator actions and building the transaction of data that is to be sent. In the PLC scenario, this is managed through decision logic closely coupled with the PLC’s operation, accessed in a high performance way through backplane communications. The second requirement is to send data reliably. The most important requirement around reliable data transfer is simply a store and forward mechanism, the ability to buffer data while a resource such as a network or server is unavailable. This appliance delivers a third benefit, an easy to use configuration environment that removes any need for scripting or code development. The Appliance is simply and quickly configured through a set of menus. This menu for example, shows the mapping of PLC Data to fields in a Relational Database Table. Other menus will set up PLC Communication and Database Communications.
eATM Data Mapping Configuration
The new trick – Requesting Data from the Enterprise
Data upload to the enterprise has been addressed a number of ways in the past, and can quickly be accomplished through the integration of a number of products. The reverse is far from true. The transfer of data from enterprise systems down to the plant floor has typically required custom developed solutions that are delicate and costly to maintain.
There are a number of items to consider when planning data integration from enterprise systems to the plant floor. First, when is the transfer required? With the PLC in control of the process, it should know best when new data is needed, yet most integration scenarios rely on enterprise systems to poll PLCs in order to know when to affect a transfer. Obviously, this creates needless automation network communications traffic. Another major issue can be the latencies inherent in enterprise system queries. Will they deliver the information fast enough for the operation of plant floor equipment, or will their sluggishness create work cell idle time? This latter problem requires a good knowledge of your systems, and some planning for the data transfer. Can data be requested as needed, or should it be batched, enabling the plant floor to request sets of data for processing (send me the next 100 serial numbers to produce, send me the upcoming 5 work orders, etc.) This technique will enable continued operation in the event of system sluggishness or even network downtime.
eATM Triggering Stored Procedures to Request Data
There is another significant benefit to an Appliance approach, with regard to putting the PLC in charge of Enterprise Integration. The use of an intelligent appliance will remove the need for changes in the PLC program (for data uploads). The Appliance can access data through the PLC Backplane, removing the need to stage data through I/O communications or storage registers. This obviously reduces integration time, and removes an additional burden that could impact PLC CPU cycle times. Enterprise data downloads will likely require PLC Logic integration, unless there was advanced thought given to enterprise integration for control purposes.
There have been significant enhancements in the integration of plant floor and enterprise systems. Standard products, delivering configurable operation take the complexity out of the initial setup, and deliver additional benefits on overall cost of ownership and reliability. But they also require looking at the problem with an eye toward putting the PLC in control of the Enterprise Transactions. Taking this small and simple step, will deliver solutions that are higher in performance and will improve your automation network bandwidth.
About the Author
Roy Kok has been involved with the automation marketplace for over 30 years. He has worked with industry leaders such as Intellution, GE, Kepware, and how offers Business Development - Sales and Marketing consulting, through AutomationSMX. Contact Roy@AutomationSMX.com
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