Nov 15, 2021

Migrating a distributed control system (DCS): upgrading computer-aided HMI

  • Article
  • distributed control system
  • DCS
  • HMI
  • human-machine interfaces

In a previous blog article, we discussed a crucial stage in the phased migration project for a distributed control system (DCS), i.e., the first component of the operational infrastructure upgrade phase.

In this blog article, we look at the second component of that phase, which focuses on upgrading human-machine interfaces (HMIs). According to phased modernization, an approach that helps minimize transition-related risks, it is now feasible to upgrade DCS operator consoles in line with the new operational infrastructure implementation

  1. Real challenges

    New technology alone doesn’t guarantee a successful migration. During our work, we often have to migrate an HMI console and realize how complex it is to modify. In many cases, the original configuration was carried out by various work teams, who do not all adhere to the same standards when it comes to control logic and its graphical representation. Not to mention how difficult it is to find someone who knows the history behind this, and that there is often little documentation on the HMI configuration.

    Migrating older HMIs to newer display technologies may prove to be even more cumbersome when the logic is embedded directly in the screen pages or when an excessively large quantity of graphic objects has been used, which could affect performance and dynamic behaviour. For example, overusing poorly defined tags in HMIs inevitably generates errors during manual conversion and makes the system hard to operate.

    Even if it’s always possible to manually migrate a small number (100 or fewer) of HMIs, doing so on a larger scale (300 or more) usually leads to a range of problems during the project, including very long execution delays, budget overruns, unequal implementation of client standards, omissions and implementation errors. To reduce project costs, some manufacturers turn to an overseas group to have the bulk of these modifications done manually, with a different group carrying out the commissioning— thereby resulting in quality issues upon reception of the system and delays in transitioning to the new system. Lastly, these systems sometimes need to be completely reworked by the plant staff because of a lack in knowledge transfer among the various stakeholders.

    A proven tool

    To avoid these kinds of situations and facilitate the transition across HMI technologies, BBA has, over the past 25 years, developed a universal graphic converter (UGC) tool to manage all this complexity and perform a predictable migration of older technology to a newer one.

  2. This very high-level tool works as follows:

    1. Preparation and extraction of “classic” HMI data.
    2. Scrubbing, analysis and backup of data extracted in a database system.
    3. Generation of “modern” HMIs based on previously processed data.

    Once the first two stages are completed, conversion reports can then be generated for the client indicating the errors or discrepancies to be corrected before migrating to the new technology. This makes it simpler to assess the effort required and ensures better decisions to adapt more easily to the new features offered by the selected technology.

  3. The previous preliminary analysis report for a PPB-type HMI migration to the 800xA (PG2) system may seem cryptic at first glance. However, by using the appropriate indicators, one can quickly recognize the scope of the task to be accomplished.

    • HMI component
      • 718 graphics to convert consisting of:
        • 1,962,459 static or dynamic graphic elements to process
        • 52,406 inputs in contextual menus (Figure 2)
        • 1,011 configured trends
  4. These indicators help define the project scope and efforts required for the migration. Using the UGC tool substantially reduces the efforts required by automating the transformation in a way that enhances the possibilities offered by the new system, without losing any of the features and engineering developed over the years by plant staff. Furthermore, this tool offers detailed analysis reports so clients can correct any errors early in the process or get the guidance they need to help them in their decision-making process during the project. BBA’s migration plan doesn’t simply entail replicating a system but also offers an opportunity for improvement by working closely with our clients. Once these corrections are made, BBA is then able to automatically generate HMIs geared to the target technology. Manual interventions on HMIs are reduced to a minimum to avoid human errors.

    BBA’s UGC technology enables clients to maximize their return on previous HMI investments, while providing a springboard to new display technologies. As such, BBA can help its clients unlock the full potential of display technology using major players offering:

    • ABB 800xA
    • Emerson DeltaV Live
    • Rockwell Automation Factory Talk View
    • Siemens – WinCC
    • Wonderware Archestra and Intouch
    • Foxborro
    • Autodesk – AutoCAD (HMI drawing conversion)

    Two possible approaches

    During the generation process, a symbol library meeting quality standards could be developed, and more efficient navigation would also be available.

    To reduce operator adaptation time and costs, an initial approach proposed by BBA entails fully replicating the existing system. A second approach, requiring greater involvement by the plant, calls for rethinking HMI ergonomics based on the abnormal situation management (ASM) standard or high-performance graphics (HPG) standard. BBA recommends a one-to-one conversion to facilitate the transition for operational teams, as well as an in-depth modification of the HMI design in a modernized technological environment, when budgets and resources become available.

    To learn more about BBA’s IT/OT solutions for industrial environments, feel free to contact our team.

This content is for general information purposes only. All rights reserved ©BBA

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