By Dan Hebert, Senior Technical Editor
When it comes to directly linking process plant-floor automation with ERP systems, theres lots of talk, but relatively little action. Despite years of discussions, seminars and product announcements, actual applications making this linkage are few and far between, in spite of the very real benefits of linking the plant floor and the enterprise. So why has the rhetoric outpaced the reality?
One reason is overwhelming implementation complexity of most plant-floor/ERP system integration projects. This complexity probably is engendered by the skill set required for implementation, and causes an initial inertia. To understand the integration challenge, one needs to be very well-versed in process plant automation systems and also something of an expert in corporate computing systems.
If no one individual or department has the required skill sets, then close cooperation is required between process automation and ITan uneasy alliance at the best of times.
If lack of skills and difficulty cooperating makes in-house integration of plant floor/ERP systems tough, then the first option is to seek help outside the company. However, the inherent complexity of such projects makes it very difficult to write a specification that will attract competing fixed-price bids.
To submit a fixed-price bid at a reasonable price, a supplier must understand the project completely, and many suppliers lack the same dual skill setboth process automation and enterprise computingthat end users lack. The lack of clear specifications and a shallow pool of fixed-price bidders is a significant barrier to integration implementation.
Instead of submitting a fixed-priced bid, most possible partners want to charge customers on a time-and-material basis for studies to establish project parameters. This blank check approach is not a pleasing proposition for many companies, so inaction results.
But there are ways to get the job done. One is a two-step process.
First, tie the plant floor to the middleware using process automation folks working with familiar suppliers and system integrator partners. Second, have the IT folks tie into the middleware. Middleware suppliers generally know enough about both process automation and IT to work successfully with both groups.
Notice that no direct links are made between corporate computing systems and plant-floor automation systems. Instead, the middleware establishes a demilitarized zone (DMZ) between process automation and IT that provides a place where plant-floor data can be transformed into formats recognizable by ERP systems and vice versa.
Still, direct links between the plant floor and higher-level computing platforms, such as ERP systems, should be much more efficient than using a DMZ, at least in cases where required data exchange is limited. For example, 3M España in Madrid directly connects its Rockwell Automation ControlLogix PLC to its Microsoft SQL database. The link allows a few hundred recipe parameters for production of the companys various Scotch-Brite sponges to be transferred from the database to the PLC.
3M uses our xCoupler enterprise transaction module, which plugs right into the ControlLogix backplane, says Ron Monday, president and CEO of Online Development, maker of data bridge appliances.
The module has an MSSQL software adapter specifically configured to exchange data with ControlLogix. The modules bidirectional capability enables data to be sent from the PLC to the database confirming that proper recipe parameters have been configured, he explains.
Consequetly, there are some simple, quick and relatively inexpensive ways to link plant-floor controllers with higher-level computing platforms and ERP systems, but only for certain applications that meet strict criteria. For most integration projects, complexity and confusion still reign.