MDT Software: Change tracking helps pet-product provider reduce lost code, plant downtime
September 11, 2009 by André Voshart
THE COMPANY: Nestlé Purina PetCare Co. is a global manufacturer of pet products with a plant in Mississauga, Ont.
THE CHALLENGE: Before MDT AutoSave Change Management Software was installed (first at the Nestlé Purina plant in Mechanicsburg, Pa.), the plant used a homegrown program to track changes in their programmable devices. About 15 programmers regularly made changes by accessing the most current program from Explorer, making changes and then saving the new version of the program back on Explorer. “We really had no way to manage all the different program versions created by our programmers,” controls engineer Alan Hiler explains. In facilities where multiple people are making changes from multiple computers, the documentation of changes is often lost, archives of older copies are non-existent and the wrong programs may be running on the devices. In environments requiring frequent changes, it is not uncommon for code to be lost or changes overwritten resulting in increased downtime and decreased productivity.
THE STRATEGY: “We made the decision to use AutoSave because we wanted to get away from having different people making changes and not documenting it properly,” Mark Buettner, director of electrical and controls, says. “We didn’t want a situation where an emergency occurs, such as a processor dies, and production is stopped because we don’t know where the latest version of the program is located or have to decipher which program is the current one.”
THE RESULTS: In providing a central repository of all program changes, AutoSave ensures that, if a device fails or a program results in undesired performance, a prior version of the program is readily available so plant operations can be restored quickly and correctly. “With AutoSave we can easily download the previous copy of the program and get things running again quickly. If one device is down, the entire plant could potentially be down, so the ability to get up and running again is very important,” Hiler says. Stopping production because there are no older versions of a program available is costly enough but consider the cost associated to completely rewrite a program. “If you lose a copy of a program, it isn’t just the production time we are losing, but we also lose the intellectual value of the program we have created,” Buettner says. The cost to re-write, test and commission a single program is often greater than the cost to implement a change management solution.
“Before AutoSave was installed in the plant, we had some problems with program version mismatches, the biggest issue being the assumption that the copy on file was the program running in the PLC, but in some instances, it was not,” Hiler explained. “MDT AutoSave periodically queries automation devices and compares the code running in the processor with what is on file. If a mismatch is detected (indicating someone went around the software to make a change), an e-mail notification is sent highlighting the mismatch along with information pinpointing the changes. This ability to regularly verify that the correct version of the program is running significantly decreases product waste and safety risks.
“A big benefit for us is AutoSave’s ease of use for our maintenance guys.” We have guys here that have never accessed a PLC program before and they have to download a program to make a simple change. Before AutoSave, we had to write pretty detailed documentation on how to find the file, open it, connect to the server and so on. Not only does AutoSave save us time, it also significantly reduces any chance that the wrong PLC is accessed, causing big safety issues,” says Hiler.