Powder Coated Tough - Fall/Winter 2007 - (Page 35) conveyor PLC. Again, photo eyes are used to detect the presence of product on the hanger. Operator Interface There are multitudes of configurations for operator interfaces. A control system is no longer limited to just push buttons and indicator lights. Real time data from the PLC can be displayed, monitored, and modified through a graphical type interface in a format that is easily understood by the operator. Selecting an interface depends on the needs of the application. Simple interfaces range from text based, line display terminals to graphical terminals. These are used for data manipulation and alarm enunciation. Often, these terminals can be implemented to read data from multiple PLCs within a system. More sophisticated systems may employ a PC (Personal Computer based interface. These systems offer the user a much higher level of functionality and connectivity. Because the interface is a PC, data from the PLC can be written to a mass storage device, such as a hard drive. Recipe data also be stored on the PC and written to the PLC on an as needed basis. The logging of system status, history, and faults to the PC greatly enhances the maintenance of the system. By interfacing the PC to a network, PLC data can be read into other remote PCs. Data can be read directly into common PC application programs, such as spread sheets. PLCs used in conjunction with PC computers will greatly increase the systems capabilities by increasing data acquisition, storage and trending information needed today by many companies for SPC and or internal ISO 9000 reporting. Security measures can be employed on the operator interface to prevent unauthorized modification of PLC data. Passwords are employed to restrict access to given areas. Access to these areas can be logged to the PC as a permanent record. Using a PC for an interface can also greatly improve the appearance and usability of a system. Color displays and animated graphics help to provide information in a userfriendly manner. PLCs offer a unique feature to the complete system, however, they are not without their faults. The controller is subject to things like lightening strikes, or even physical damage. If the system is designed without redundant manual hand off controls, and the PCL is damaged, your system can be rendered inoperable until a replacement is installed. Having current program back-ups on hand is important so that replacing your PLC can happen quickly. A nationally supported manufacturer can usually help you find a replacement within a day. Improving the efficiency of a powder coating line is very important. And those companies that take the time to investigate and implement any of the new tools and automation concepts will find their products being produced with a superior looking finish while realizing improved performance of the finishing line. But those that choose to do nothing in regards to automation will continue to find their operational cost spiraling out of control. Jeff Hale is director, sales and marketing, at ITW Gema, Indianapolis. He can be reached at 317-298-5161, or visit www.itwgema.com. Powder Coated Tough 35 http://www.wisconsininfraredsystems.com/pct http://www.wisconsininfraredsystems.com/pct http://www.itwgema.com http://www.wisconsininfraredsystems.com/pct
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