Developed jointly by the Society of the Plastics Industry (SPI) Machinery Div., Washington, D.C., and the Euromap Technical Commission of Frankfurt, Germany, the new standard enables data from any make of molding machine to be passed on to a host computer. "It's a universal way for data to flow from a molding machine to a computer," says Tom Thomas, chairman of Syscon International of South Bend, Ind. Syscon's PlantStar Div. has written software for equipment makers to test their controllers' compatibility with the standard.
Data exchange takes place through the network file system used by Ethernet--as well as some other types of networks. "The molding machine simply writes the data into a text file that the host computer can read," explains Tom Richards, who manages electronics and control development for Van Dorn Demag Corp., Strongsville, Ohio. He also served on the committee that wrote the standard.
Richards says this reliance on network file sharing sets the new standard apart from now-obsolete communications schemes--like the earlier SPI protocol--which employ a multitude of commands to pull data off the machines serially.
Right now, a finished communications standard exists only for injection molding machines. But SPI Machinery Div. Director Walt Bishop reports that similar standards are being developed for extrusion and blow molding controllers.
Making monitoring easier
Once the new standard becomes integrated into the next generation of machine controllers, it should make process monitoring more accessible to all types of users. On the low end, it could completely eliminate the need for commercial monitoring systems' proprietary hardware and software. On the high end, it will make it easier to pass data into third-party process-monitoring software. "Monitoring can be a real headache with existing technology," says Richards. "This standard makes it easier for everyone."
According to Richards, the standard will enable molders to print out simple reports of process data without any need for a process-monitoring system. Any molder would be able to link an ordinary PC to a molding machine and print out a batch file of process data such as temperatures, pressures, and speeds. While this format would contain raw data in a simple text file, it would be understandable by molders, says Richards.
Moving up a notch in sophistication, this same batch file could easily be exported to an Excel or other Windows spreadsheet for data analysis or just a better-looking presentation. Richards adds that simple Windows programming commands (DDE commands, to be specific) will permit the host computer to automatically update a spreadsheet program with fresh process data at preset intervals.
No more 'Boxes'
While the standard probably won't eliminate commercial plastics process-monitoring systems, it will certainly change their configuration by doing away with their machine-side data-acquisition boxes. "This will be good for processors and potentially negative for us," admits Thomas, who notes that software represents only about one-third of the price tag on a $100,000 process-monitoring system. "Hopefully that one-third will remain when the rest of a plantwide system gets sucked into the machine controller," he says.
On the other hand, the new-found ease of monitoring with the SPI/Euromap standard could translate into a dramatic increase in the number of molders who install real-time monitoring. Thomas even predicts a 'flip-flop' of current conditions, in which only a minority of molders have monitoring capability while a majority do not.
And Richards notes that commercial process-monitoring systems provide value in the form advanced data analysis, SPC, production reporting, scheduling, and other features not easily accomplished in a do-it-yourself spreadsheet.
Though the standard is finished, machine-interface boxes won't disappear overnight owing to the large number of existing machine controllers that lack networking capabilities, predicts Mick Thiel, president of Mattec Corp. in Loveland, Ohio. "Due to this large installed base of older machines, the boxes will still come into play for some time," he says. Thiel adds that he looks forward to the day when data-acquisition boxes are extinct "That will be just fantastic," he says, citing the high costs of developing hardware and scores of PLC interfaces.
Syscon's Thomas also does not foresee the disappearance of machine-interface boxes until machine controllers universally have built-in "smarts" to hook up directly to Ethernet or other standard computer networks. "It will take a long time to get to that point--maybe as long as 10 years," he says.
Until then, Thomas predicts that most monitoring systems will operate as a hybrid in which some controllers hook up directly to the network and others will use interface boxes.