Blog Post by Shahrokh Yousefi, Controls Engineer
One of Patti Engineering’s pharmaceutical industry customers wanted to upgrade their current production equipment for manufacturing medicated adhesive patches (transdermal patches). The improvements to the machines’ functionality would boost both production quantity and quality, and also allow easier maintenance for the operations team.
Patti Engineering developed a custom solution to meet all the customer’s many requirements, which included updating the current control system to:
• Count completed parts and stop the machine after a predetermined number have been manufactured
• Allow air nozzle changes
• Modify the machine’s movement for rejected parts in the reject station
• Resume normal operation after a stop when a predefined number of rejected parts has been reached
The control system hardware uses a Siemens SIMATIC S7-200 series PLC and a Siemens SIMATIC TP 277 HMI panel as user interface. The software used to modify the PLC was Siemens Step7-Micro/WIN and to modify the HMI panel was SIMATIC WinCC Flexible. Unlike typical SIMATIC S7 PLCs (300 and 400 series), the only way that SIMATIC S7-200 communicates with the programming device is PPI protocol, so we used an adaptor to communicate via USB port. We connected to the PLC, retrieved the running program, and created the modifications. The program was then validated and deployed.
As with any controls improvement project, the customer was concerned with having unplanned interruptions of production during validation. The above-mentioned software does not have simulation capability to test the new logic offline. However, by triple-checking our program changes and reviewing the logic with PLC based mindset, we experienced very few unexpected results during the installation and test phase. This allowed us to stay on schedule.
The maintenance and production teams were both happy at the end of the project. Our solution made the equipment easier to operate and also increased key quality and quantity indexes.