Upgrading PLC Hardware, Do It Right

October 2, 2017

Legacy Migration

By: Jacob Chapman, Manager, Client Solutions at Grantek Systems Integration

As a systems integrator, Grantek has the opportunity to see the insides of new facilities every day.  We see what some do better than others and regularly discuss strengths and weaknesses with our clients.  With this experience, Grantek harnesses incredible knowledge of what industrial facilities do well, what they can improve on, why decisions are made, how they can improve their output, and what improvements will be most effective for them.

One example Grantek notices, which can have a monumental impact, relates to customers holding onto deprecated PLCs. Specifically, when upgrading PLC hardware, do it right!  Don’t do the bare minimum.

What is the “bare minimum”?

Too often, Grantek observes small integrators performing PLC upgrades using automatic code conversion tools.  They do this because it’s fast, easy, and can be done inexpensively. While cost savings are important, these automatic code conversion tools do pose some risks:

  1. The code output from the tool is messy, impossible to follow, and left like that for maintenance to struggle with.
  2. Data and tag names are left as gibberish based on old PLC-5 tag conventions that don’t make sense in new PLCs.

The conversion tools create an environment that allows issues to grow as time passes.  Adding code into messy code usually leads to more mess.  This all leads to ongoing and increasing future costs.  Troubleshooting, maintaining, and improving the code later will cost more than it would have to “do it right” during the upgrade.

Do these quick-fixes occur so often due to negligence and poor decision making?  Of course not.  The customers’ focus is often in the here-and-now to maintain uptime and fix immediate issues at hand.  At times, there is a strong “if it’s not broken, why fix it” mentality at play, and everyone has a budget to work within. Its important to understand the missed benefits of completing a proper PLC upgrade and to equip your team with the tactics to achieve the company support required to do so.

Understanding the Benefits of a Proper PLC Upgrade

PLC Upgrade requirements should be geared towards enabling specific business needs.  For each company, some aspects will be more important than others.  Above all else, avoiding automatic code conversion tools should be a top priority.

It will take more time to complete the PLC upgrade, so it will cost more, but it will save you money in the long run.  Count on it.  Recall the above-mentioned issues; maintenance forced to work with confusing code, causing more downtime and taking longer to get back up, lost production, etc. Consider the long-term solution rather than the short-term gain.

If your company has committed to upgrading PLC hardware, consider also exploring additional options.  It will save the company costs to review at the same time:

  1. Factoring in logic to calculate workcell metrics or Overall Equipment Efficiency
    This helps to identify which areas of the plant are performing sub-optimally to others, understand why this is, and determine how to improve the plant overall. If well executed, this is an exercise that will show an Return on Investment.
  2. Set standards for data collection and implement consistency
    In order to compare one filler to another in a one to one comparison, when comparing different OEMs, similar data points on each are needed. This is the best way to compare accurately and drive improvement throughout the plant.  with the same theory applies to palletizers, laners, inverters, etc.  Set standards and implement them as new projects arise over time, to realize increased value at a fraction of the cost.
  3. Implement programming/engineering standards focused on making maintenance’s life easier
    Imagine programming that has tags to alert designated users when something in the programming is wrong; similar to alarms for equipment, but for the programming itself. Compare this to code output from conversion tools that have tag names made up of random numbers and letters, code jumps that are impossible to follow, etc.  The difference in time spent debugging the latter is significant.  There are several engineering standards worth implementing. Completing these in tandem with PLC upgrades presents a great opportunity.
  4. Consolidate calculations that should be in the PLC into the PLC
    Grantek works with customers that have SCADA programs performing messages/calculations in the script of an HMI screen button. We also see customers that need to calculate significant amounts of data for reporting and do so in the reporting platform.  This results in applications that work slowly, functions that only work sometimes, or the need to press buttons over and over until the application works.  Focus on solving these problems while completing the upgrade and make everything run better.
  5. Update communication paths to use newer technologies (e.g. serial to Ethernet).
    If the commitment has been made to update a PLC from old to new, the new PLC should not use archaic communication technologies. It is counter-productive to buy hardware that will need to be replaced soon anyway.  This also robs systems of future capabilities, such as improving accessibility, monitoring and management capabilities.

When completing a PLC Upgrade, it is important to focus on what will most benefit the business and processes. Consider the long-term benefits of investing in a manual conversion and eliminate the risks of having to revisit the code, resulting in additional costs.  Consider exploring other investments while completing a PLC upgrade, saving the company in completing a full spectrum review.

Grantek is pleased to provide information on how to complete a PLC Upgrade and when to let go of PLC-5 and move on to CLX. For more information, please contact Grantek today.

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