Open-Source HMIs for Packaging Machines

Joe Ambrose is the Digital Innovation Program Manager for BW Packaging Systems. The following content contains excerpts from his interview with Control Design, which originally appeared on controldesign.com on February 25, 2022.

Earlier this year, Control Design invited me to answer a reader's question about open-source HMI software. The reader asked, “What are the advantages and drawbacks of open-source HMI software? And what sorts of additional hardware might be necessary?” After conferring with our larger digital innovation team, we shared the following insights with Control Design’s readers.

How Familiarity Impacts HMI Selection

One of the key design elements is knowing what the end-users are comfortable with. In many cases, our organizations want a particular HMI^{A human-machine interface (HMI) is the dashboard through which an operator interacts with packaging systems or equipment. Modern HMIs can offer operator training resources, provide preventative maintenance reminders, assist in troubleshooting machine malfunctions, and much more.} based on previously installed equipment or familiarity. This can limit the available options when considering open-source development platforms as most HMIs are purpose-built and require a specific, commercially available development platform.  When there is flexibility or requirements to use open-source development platforms there are 2 key advantages:  Flexibility and Licensing costs.   Full control and configuration of the software is possible as the source code of the development software is available. A sufficiently skilled engineer would be able to create software tailored to a much more unique end-user experience, or bespoke solutions for a customer request.  Open-source software usually means no licensing costs for development software.  This may be an advantage but would be dependent on the implementation.  Most open-source solutions will require an IPC-centric solution, which may require additional equipment (UPS, data concentrator, hosts, screens, etc.) that would offset the savings. 

Considering HMI Total Cost of Ownership (TCO)

For the developers and the end-user, total cost of ownership (TCO)^{Total cost of ownership (TCO) refers to the long-term costs associated with owning and maintaining a packaging line or machine throughout its entire lifecycle. TCO includes costs associated with the purchasing process, plant operation, machine maintenance, and technical support.} is always important to balance when considering open-source platforms.  As with any open-source community development, there is a nice starting point to build upon new functionality and capabilities into the code for the specific application or use case. However, unless contributions are made back to the community, there is a risk of compatibility issues with updates to the open-source environment. Furthermore, forking from the community puts a larger burden on the adopter to maintain and address issues with the starting point.  There is a need to consider whether an organization has the right blend of software and controls engineers to support the development and maintenance of a system, which can add up to a big expense in the long term.  Getting a team trained and then appropriately staffed can take a lot of resources away from the development of the solution.

PLC Integration and Other Technical Considerations

In addition to cost, there are a few other technical considerations including fault tolerance^{Fault tolerance refers to the ability of a piece of equipment (or of a system) to continue to operate even if one (or more) of its components has failed.}, security, and additional software.  Controls systems tend to have high fault tolerance with the ability to quickly replace hardware and redeploy applications where PC-based solutions are not so friendly.  Most commercially available solutions come with cyber security certifications that open-source solutions cannot offer or may not maintain.  This is particularly worth evaluating when handling data.  Open-source software may not natively support required PLC^{A programmable logic controller (PLC) is a hardened controller engineered to control manufacturing equipment and processes.} communication protocols, necessitating additional software to translate this into a format that is supported.  Generally, there is a cost associated with this software which would be a per-unit cost.