A primary goal is to harmonize the design of HMIs and to develop a consensus, especially among end users, on what the standard screens would look like and the content on each panel. Once end users complete the specification defining a specific set of HMI screens, machine builders will be able to reconfigure operator interfaces on different machines to meet the standard.
"The obvious benefit for end users, as the line is staffed with operators, is that on any given day, if someone calls in sick, someone else can cover that piece of the line," Doney said. "It's much easier for them to do that as they interact with the machine if the status of the machine looks the same as other machines on the line that they have worked on and, when a fault occurs, they are displayed in a similar manner."
On-screen machine diagnostics
A fundamental difference between process and packaging for Nestlé is that the company develops its process technology internally and therefore intimately understands and owns the intellectual property of the control code. Packaging machinery is developed by many different machine builders, and Nestlé does not want maintenance personnel accessing code that is not natively familiar.
Griffen called for machine builders to make all diagnostic and corrective actions accessible on the HMI, rather than inside the controller. He recognized that this will require a new effort from most suppliers, but he said it will add value by reducing downtime and improving efficiency.
This second element of the HMI transformation changes the way diagnostic information is displayed and will enable more parameters to be adjusted using the HMI interface. The engineering goal is for the standard to be implemented in a consistent way between different types of packaging machines with a familiar and almost identical program structure.
"What operations needs is a common look and feel so that a function, such as labeling a package, uses a set of HMI screens that are similar to the screens used to gather packages and place them in a box," said Doney. "There is a difference in the value-added steps performed as you move down the line but, for each of the process steps, an operator can walk up and the screens look the same and provide similar types of functional information. Plus when a fault occurs, the process of resolving problems is similar from unit operation to unit operation."
The PackML standard becomes an important part of the solution and provides the basis for creating a set of consistently named variables and tags. Doney said food companies generally put a lot of emphasis on their own core competence, but historically there hasn't been an emphasis on unit operations downstream from the filler. If there isn't appropriate attention on the downstream operations, an entire line can be brought to a halt due to problems with the material or machine.