Transitions Optical, a leading global manufacturer of photochromic lenses, had successfully used programmable logic controller (PLC) driver software and Microsoft Visual Studio.NET to build applications that integrated the company’s automated equipment on the factory floor with its manufacturing and business databases. Transitions Optical then decided to expand on the enterprise resource planning (ERP) implementation by building a human machine interface (HMI) application for the equipment that would support both machine control and visualization. The manufacturer had been using the Allen-Bradley application development environment PanelView to program some of its machines. However, a more functional approach was needed to code an HMI application for highly automated equipment such as laser etching and packaging machines that required operator interaction. The challenge was finding a cost-effective way for the HMI to communicate with the PLC.
To cover all the bases, Transitions Optical first evaluated proprietary software from larger HMI suppliers including General Electric, Siemens and Allen Bradley. But it discovered that although some packages offered a complete PLC programming solution and were therefore convenient, the proprietary approach could result in licensing and annual maintenance fees of tens of thousands of dollars. That’s because costs depend on pricing from the software publisher and the number of development licenses, data points, add-on components, and runtime licenses. The company opted to expand on its use of “alternative” PLC driver software from CimQuest INGEAR because the software costs only a few hundred dollars, while supporting the same functionality as proprietary packages.
Specifically, Transitions Optical used INGEAR NET.LOGIX to gain access to its Allen Bradley PLC memory, databases, I/O and communications. The software lets programmers easily get information from the PLC and use the data to build the HMI application. The HMI can then send commands back to the PLC for control as well as receive data from the PLC for visualization. The new implementation handles functions such as alarm annunciation, calibration, parameter editing, manual control, operator access and log viewing.
The software works well for manufacturers in several ways. Transition Optical’s ERP implementation based on Visual Studio.NET, for example, provided a component that let it connect the factory floor to the main relational database. With the new implantation, all the data about tasks performed by manufacturing operations now get stored in the database. Five or six HMI applications that are deployed across numerous machines on different lines tie to the database and all the data about manufacturing operations they perform get stored in the database.
In addition, .NET code ensures the operator is authorized by checking the database. This lets Transitions Optical “slice and dice” data by operator, shift, product, or work order and then run reports on the information. Operators can also scan a work order or a matrix etched onto the lens and this data is then used for identification purposes in the rest of the manufacturing process. For instance, an HMI visual lets the operator double-check that the correct lens is being loaded into the right box. In one example, a robot behind the packing line sorts out boxes and puts them into one of 16 smaller conveyors that then feed the boxes onto a large conveyor line. A control in .NET uses PLC data to update the HMI in real-time, giving operators a visual representation of how many lenses are on which conveyor lines.
The company also uses the HMI application on machines such as its Cognex Vision that inspects the lenses. A .NET piece of code waits for a message from the PLC. When the PLC gets the message, it knows the machine has indexed and the lens is sitting under the camera ready to have its picture taken.
Another piece of equipment uses a laser to engrave a data matrix onto the lens. Here, the PLC driver tells the HMI that the lens has been gripped and is in a stationary position for the laser to be fired. The PC program causes the laser to fire and then tells the PLC that the machine’s gripper can release the lens onto the conveyor belt.
The INGEAR/PC/PLC software, along with other components that let users program PLCs themselves, gives Transactions Optical and other manufacturers the same functionality as proprietary software but at a much lower cost. In Transactions Optical’s case, the company pays for the Developer’s edition, but the runtime licenses are free, which cuts licensing costs. In addition, deployment is unlimited. Other advantages include that it’s relatively easy to find Microsoft Visual Studio.NET programmers — and it’s not necessary that they know a lot about PLCs. Currently, the company’s HMIs connect to its Rockwell ControlLogix PLCs via Ethernet, which makes data exchange very fast as well as helps support the networking of Transitions Optical’s automated machines.
Steve Cicco is a Senior Systems Analyst for Transitions Optical, Inc. which focuses on the integration of information technology within process and factory automation.