Automating Manufacturing Processes with Linux
With the real-time task up and running, the next step was to build the user interface for the project. The GUI was one of many tasks in our program that did not need to be accomplished within hard real-time restraints. We did not have heavy concerns for system resources, because our real-time module would execute within our established hard real-time requirements. We selected KDevelop IDE and Qt Designer GUI builder from Trolltech for programming the interface. Qt Designer allowed for the development of a GUI with signal and slot interaction with functions in the KDevelop program. The result of developing with the combination of the two packages was perfect for our application. We were able to develop a user-friendly interface quickly.
The program was written to utilize two forms of information feed to the system: the digital inputs from the DAQ card and the human operator interaction with the GUI. The combination of the two was needed to maintain the integrity of the data. For example, the operator would enter the part number for the job being manufactured. The data that was gathered during the run would be tied to the part number. This replaced the old method of having the user tally information on handwritten forms.
Gathering the data was only the first step for the system and program. The most important aspect was to make it usable by all of the departments of the company. The scheduling department, material purchasing department and tool service departments are some examples of where the data will be put to good use.
The SmartPress program stored the gathered data in a PostgreSQL database. PostgreSQL also is our enterprise back-end database. So, future application development will make SmartPress data visible in enterprise applications across the company.
Our SmartPress system has moved from the test bed to the production floor. Looking back, we have created a flexible manufacturing monitoring system. Using Linux, the result is an expandable system that has been customized to the needs of the company. We can adapt the SmartPress for new manufacturing processes. The system also is upgradeable. In the future, we intend to rebuild the project on a newer kernel. For the upgrade, we probably will use Fedora Core as the base Linux platform.
The SmartPress system's low hardware cost is important as we are installing a system for each stamping press line. We cut hardware costs by using personal computers and DAQ boards that were supported under Linux. Our software development also was inexpensive. The time that Ryan Walsh spent on this project was similar to learning and developing in a proprietary controls language. Now, Ryan is fluent with kernel modules, real-time operating systems, PostgreSQL and GUI development. These skills are much more useful than learning one vendor's control programming language. For us, the do-it-yourself option resulted in lower cost, no vendor tie-in and upgraded developer skills.
Resources for this article: www.linuxjournal.com/article/7810.
Craig Swanson (firstname.lastname@example.org) designs networks and offers Linux consulting at SLS Solutions. He also develops Linux software at Midwest Tool & Die. Craig has used Linux since 1993.
Ryan Walsh (email@example.com) works as a Network Engineer at Midwest Tool & Die. Ryan spends his spare time in free fall, jumping out of airplanes.
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