Work is underway to correct this deficiency. A recent draft report, Harmonization of Industrial Automation Standards, also known as ISA TR 88-95.01: Alignment of ISA-88 and ISA95, is a major step in resolving the issues. The marriage proposal was submitted to the ISA Standards and Practices Board on July 15, 2008, for approval and publication. TR-88-95 recognizes that automation involves more than just batch control. (Table 1 illustrates that all types of manufacturing are involved).
In a classic case of practice what you preach, ABB uses ISA88 and ISA95 in its own manufacturing operations. Leroux explains: Several years ago, ABB was looking to modernize the workflow and information exchange in our factories, which produce electrical components, such as circuit breakers, switchgears, motors and drives. The initial reaction was to use the technology and solutions that ABB provides to other manufacturers in the process industries. ABB already provides solutions based on ISA95 for hybrid manufacturersthose that have a mixture of batch, continuous and discrete in their facilitiesso using the same solutions for our discrete manufacturing sites made sense. The ISA95 solutions for ABB factories are being rolled out worldwide and use ISA95 for communication to the business system layer, scheduling, processing, tracking and reporting of materials throughout the facilities.
The TR88 report identifies key areas of overlap and gaps between ISA88 and ISA95, and shows how to make the interactions work. Its just the first step in the marriage between ISA88 and ISA95, but it shows that progress is afoot. As ABB and others have demonstrated here, ISA88 and ISA95 arent just for batch any more.
Getting into Discrete
ISA88 is moving into discrete automation, too. John Parraga of Rockwell Automation used ISA88 to automate an anodizing application that involved robots, robot controllers, cranes, processing tanks and part ID tags. The control portion involves regulatory control, monitoring, interlocking, exception handling and repetitive discrete managed as sequences.
We used Rockwell Automations FactoryTalk Batch to define the system, says Parraga. First, we used the equipment editor to define what the plant equipment is capable of doing. Then, we used the recipe editor to define the procedures that coordinate the equipment. If the equipment isnt capable of performing the function, the recipe editor wont permit it.
FactoryTalk Batch provides sequencing instructions as well as the equipment arbitration needed to carry out tasks, and then downloads commands to the controller or to an operator to perform a task manually.
Parraga says Rockwell Automation is using the ISA88-based FactoryTalk in several other non-batch applications. In one application involving manual assembly of high-reliability military batteries, we use ISA88 to define every step in the process, he says. The system tells the operator exactly what to do, checks quality measurements and logs everything.
Hes also involved in a brewery routing application, which has many storage tanks and many filling stations. Connecting these is usually a job for PLCs written in relay ladder logic. Parraga is using ISA standard concepts to determine routing instructions involving tanks, valves, pumps and filling stations. ISA88 organizational concepts help determine what has to be done to get beer from any tank to any filling station.
Applying ISA88 design principles is beneficial to a wide range of industries, says Parraga.
Rich Merritt is a contributing editor to Control.
To read the second part of this article, Getting into Discrete, which describes how ISA88 can be used to control robots and packaging operations, and to find out more on discrete manufacturing and ISA88, go to www.controlglobal.com/0809_Domino.html.