How to lower PLC software costs


How to decrease software costs

Figure 3: PLC software from vendors like Ingear costs much less than similar software from PLC vendors and doesn’t require run-time licenses. Courtesy: CimQuest IngearAlternative software solutions exist on the open market from several vendors (Figure 3). Doing some research reveals these alternatives.

Getting users and machine builders to talk about how they avoid these costs by purchasing alternative software is difficult. In many cases, they have built relationships with their PLC vendors over the years and have standardized on the PLC hardware. They don’t want to damage that relationship.

For example, a major automation vendor offers a software solution built on OPC to enable connectivity between HMI software packages and its PLCs. Once a user builds an interface application with that HMI development tool, the software provides drivers and other connectivity components that enable PLC communications. Users are then required to purchase individual software copies for every machine on which they want to run the application, along with annual software maintenance fees for each copy.

Trien Dao, senior software engineer at a major medical device manufacturing facility in the Minnesota Twin Cities region, evaluated the cost of using the server software to communicate with numerous PLCs deployed in the plant, but the license and annual maintenance fees required for each copy set him searching for an alternative. One tool he discovered automated development of OPC applications. (Working with OPC can be complex and requires specialized experience.) The software significantly simplified the process of working with OPC but still required purchase of individual automation software copies and maintenance fees, along with the cost of managing another license.

Instead, different PLC driver software was purchased. “Once we developed the interface, all we had to do is export the DLL [dynamic link library] to any machine on which we wanted to run it. We didn’t have to pay additional fees. We have PLCs running on many machines, so not having to buy additional licenses for each one is a tremendous cost savings, definitely in the six figures,” said Dao.

Mike Sluz, electrical superintendant for Wynndel Box & Lumber, a specialty wood product manufacturer in British Columbia, Canada, also purchased the PLC driver software. According to Sluz, “Wynndel faced the challenge of displaying real-time error messages and production data at various workstations around our plant.” Realizing that the software could help gather data from PLCs in the plant, the PLC driver software replaced the need to purchase and install multiple automation software licenses at more than $1,100 per workstation.

Although vendor-supplied software is proprietary, requires licenses, and can’t be modified by a customer, almost all of it is written in Microsoft Visual Studio. In other words, anything the vendor can do, a machine builder or an end user can do, too.

There is nothing secretive, proprietary, or difficult about HMI/SCADA, data communications, SQL, and many other software packages.

In fact, many such packages can be purchased from non-PLC vendors on the open market. Anything else can be developed by an experienced MS Visual Studio programmer.

All a machine builder needs from the PLC vendor is the PLC and I/O hardware and probably the programming package (although IEC 61131 programming packages are also openly available). Everything else can be purchased separately. And, in many cases, these packages don’t have expensive software and run-time licenses.

For example, the PLC driver software includes a library of programs for PLCs that programmers use to create their own customer applications using MS Visual Studio. Such software provides access to PLC memory, databases, I/O, and communications, allowing programmers to obtain information they need from a PLC, process it in a PC, and send commands back to the PLC for control. Some such software has no run-time licensing fees, so applications created can be distributed by a systems integrator or machine builder with no additional costs.

There’s no need to pay the licensing costs of PLC vendor software when alternate solutions exist.

- Chuck Karwoski is president of CimQuest Ingear LLC, a supplier of PLC software. Edited by Mark T. Hoske, content manager, CFE Media, Control Engineering,


Also see “Products to lower PLC software costs" below.  

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