23 Mar 2021, SCADA & Telemetry

Taking control of aging control systems in the water/wastewater industry

Engineers working on water treatment plant with laptop and measuring sensors

Aging, outdated control systems are a serious issue in many water/wastewater treatment facilities. Operators often struggle with obsolete equipment installed decades earlier because it’s compatible with old system code that’s too challenging to update.

In his recent technical article in the winter 2021 issue of the ISA Water / Wastewater Industry Division Newsletter, James Redmond, acting SCADAPack RTU product line manager for Schneider Electric, explains the benefits of using automated tools to migrate legacy control system code.

Here’s a bit of what he had to say:

“In even a medium-sized control system it is not uncommon for the existing code to represent several person-years of programming investment” – James Redmond, Schneider Electric

Industrial controller platforms are complex tools made from several components. There are the I/O wiring, controller hardware, control panels, networks, servers, storage hardware and operator workstations. The glue that makes all these components work together is the software, or control system code.

These days, many older water and wastewater sites have aging industrial control systems managed with old control system code, sometimes dating back to the 1980s or 1990s, says Redmond. For a variety of reasons ranging from regulatory issues to cybersecurity risks to hardware compatibility, the need to update many of these obsolete or marginal software systems is more urgent than ever. This can be a daunting job.

“In even a medium-sized control system it is not uncommon for the existing code to represent several person-years of programming investment,” Redmond explains in his article. Previously, programmers who needed to migrate that system to a newer RTU or PLC, often had to start by learning the particular code of the programmer who created the control system code years before.

Fortunately, today there are automated code conversion tools that can reduce the migration time, risk and costs involved in PLC and RTU modernization projects.

Redmond says that automated conversion is particularly helpful when upgrading an installed control system that includes the following features:

  • large number of obsolete/end-of-life RTUs and PLCs
  • large numbers of RTUs and PLCs
  • a mix of different RTUs and/or PLCs
  • a variety of unique applications

Using the Ecostruxure Control Engineering Converter, for example, operators with Schneider Electric PLCs for Modicon and SCADApack can import source code and convert it into a GLIPS language that can work with a variety of PLCs, RTUs and others, explains Redmond. That flexibility is an essential element of code translation. Redmond also recommends looking for the following features in code conversion tools:

  • Memory organization: variables, points, registers, sizes, locations
  • Data types: simple types, structures, enumerations, functions, fb
  • System libraries
  • System information: status variables, timers
  • Application structure: tasks, program organization unit

Redmond cautions that system code migrations will always involve some manual programming, but the arduous programming work will be reduced dramatically by automated conversions.

For more details, check out James Redmond’s article on pages 9-11 of the winter 2021 issue of the ISA Water / Wastewater Industry Division Newsletter.

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