Research: Controller programming methods, advice

Control Engineering 2020 research on industrial programmable controllers said ladder logic continues to dominate programming, software integration and simulation capabilities are increasing, and survey respondents seek programming flexibility. See six software-related programmable controller changes since 2018 and nine programmable controller bits of software advice.

By Mark T. Hoske July 16, 2020

Those answering the survey for the 2020 Control Engineering Programmable Controllers Report said ladder diagram programming is most used while mobile alarms, simulation and software integration are increasing. Advice includes maintaining software flexibility and performing regular programmable controller hardware and software upgrades.

Six software-related controller changes

Since the 2018 survey, six software-related changes have impacted engineers and how they approach controller programming.

1. Programming languages/methods in use for programmable controllers: Ladder logic (ladder diagram) continues to dominate, still more than 20 percentage points ahead of number two, function block diagram. Structured text increased from 38% to 44%. C programming remained at 31%.

2. Mobile interfaces for alarm functions in programmable controllers increased significantly from 25% in 2018 to 41% in 2020 among software applications for industrial controllers.

 3. Communication software methods in use with programmable controllers: OPC Unified Architecture (OPC UA) increased from 45% in 2018 to 52% in 2020. Use of MQTT increased from 6% to 15%.

4. Software integration functions for programmable controllers: Capability with prior versions decreased from 66% in 2018 to 59% in 2020, possibly from greater IT influences and/or from the need to upgrade from unsupported versions for cybersecurity reasons. Integration with higher level systems increased significantly. IIoT-cloud integration increased from 15% in 2018 to 25% in 2020; MES integration increased from 16% to 21%, and ERP integration increased from 10% to 16%.

5. Software programming, topology, setup for industrial controllers: Simulation capabilities jumped, perhaps to serve digital transformation, increasing from 25% in 2018 to 32% in 2020.

6. Software sales, services, support for industrial controllers: Online training jumped from 38% in 2018 to 50% in 2020, which is likely driven by respondents’ answers during the COVID-19 pandemic in 2020, May 8, 2020, through May 25, 2020.

Nine industrial controller software tips

The Control Engineering Programmable Controllers Report survey asked for advice. Respondents included nine tips related to industrial controller programming and software below, lightly edited.

  1. Seek the ability to incorporate code from a variety of programmable controller languages into the preferred language of choice. I want the ability to have sections of script interspersed with my ladder or function block code. It would compile inline with other code. This would help do things like shortening certain operations that are less cumbersome in one controller programming language as opposed to another.
  2. Tear down the proprietary software/hardware model for industrial controllers. More open software would allow cross-platform translations, import / export conversion. Automate code generation. Make easier integration between PAC and HMI.
  3. Keep the number of different programmable logic controller (PLC) brands and software brands down to manageable number; upgrade PLC processors and software regularly to prevent systems from becoming too old to maintain properly.
  4. Select the industrial programmable controller software and hardware from the same vendor. This simplifies support of the systems by the vendor, reduces cost and makes the maintenance easier.
  5. Stop focusing on what’s proprietary! Use only products that are fully interchangeable with everybody else.
  6. Programmable controller software should be hardware independent and easily integrated.
  7. Put industrial controllers with Microsoft Windows or Linux OS onboard to run other applications.
  8. Reduce industrial controller hardware and increase software as a service (SaaS).
  9. Include programmable controller security, artificial intelligence (AI) and Industrial Internet of Things (IIoT) capabilities, along with integration with other systems such as robots and maintenance and service requirements.

Think again about how industrial controller programming and software can help optimize manufacturing and other automated operations.

Mark T. Hoske is content manager, Control Engineering, CFE Media,


See five articles on programming in this issue, pages 26 through 41 and online. Link to the full 2020 Control Engineering Programmable Controllers Report with this article online.

See more research at

Author Bio: Mark Hoske has been Control Engineering editor/content manager since 1994 and in a leadership role since 1999, covering all major areas: control systems, networking and information systems, control equipment and energy, and system integration, everything that comprises or facilitates the control loop. He has been writing about technology since 1987, writing professionally since 1982, and has a Bachelor of Science in Journalism degree from UW-Madison.