7 Time Wasters in PLC Engineering – and How Virtual Commissioning Reduces Them

Time is a critical factor in plant construction and PLC engineering. It becomes particularly critical when the plant is already at the customer's site and commissioning is underway. At this stage, supposedly minor ambiguities quickly turn into real project problems: delays, additional costs, lengthy troubleshooting, and extra on-site days that were not originally planned.

In many projects, a recurring pattern emerges. The biggest delays rarely occur due to a lack of technical expertise. More often, the reason is that problems, dependencies, or discrepancies only become apparent very late, precisely when changes are particularly expensive, coordination is particularly complex, and time windows are particularly tight.

Therefore, anyone who wants to reduce this dynamic must start much earlier in the project, not just at the construction site.

Virtual commissioning shifts critical insights into a phase where changes can still be made with significantly less effort. Logics, processes, interfaces and interlocks can be tested in advance, before real hardware is fully available or before the system has to be tested under time pressure at the customer's site.

This not only changes the timing of troubleshooting, but also the entire way of working in the project. Instead of discovering problems only during commissioning, many correlations can be made visible, reproducibly tested and specifically secured in advance. This reduces iterations, simplifies coordination and improves preparation for real commissioning.

Virtual commissioning is therefore not an additional project step, but a lever to mitigate risks, friction and unnecessary loops in engineering much earlier.

In practice, we repeatedly encounter the same causes for delays. At first glance, they appear different, but usually have one common cause: Crucial problems are only identified when the project is already in a late phase.

1. Waiting for Hardware
When components are missing, delivery times shift, or modifications become necessary, it's not just the assembly that stops. Often, PLC development also stagnates because reliable tests are only possible to a limited extent without real signals or a complete hardware environment.

2. Errors that only become apparent during commissioning
Swapped signals, incomplete interlocks, or inconsistent sequences in the interaction of several functions often only become apparent during real operation. A seemingly small adjustment then quickly turns into a longer troubleshooting process with effects on deadlines and costs.

3. Unclear or changing requirements
When specifications are not clear or change during the course of the project, chain effects occur. Adjustments then not only affect the PLC, but often also HMI, safety, robotics, documentation, and acceptance.

4. Coordination problems between disciplines
Electrical, mechanical, software, robotics, and process often work in parallel, but not always on the same data basis. Different assumptions remain unnoticed for a long time and often only show their effect when everything has to be brought together.

5. Complex on-site troubleshooting
In real commissioning, reproducible scenarios, clear status images, or comfortable debug options are often missing. This leads to trial-and-error, many iterations, and long shifts under high time pressure.

6. Missing or outdated documentation
Unclean I/O lists, unclear interfaces, or inconsistent version statuses not only cost time in clarification but later lead to misunderstandings that become significantly more expensive during the project.

7. Long training and onboarding times
When new team members, operators, or maintenance personnel only learn on the real plant, additional pressure arises in the already critical project phase. At the same time, the risk of incorrect operation and delays increases.

In total, this quickly results in several weeks of delay and significant additional costs, without requiring technically extraordinary problems.

The practical benefit of virtual commissioning lies primarily in preventing these typical time-wasters from becoming apparent only in the final phase of the project. Logic, sequences, and interlocks can be tested in advance, even if hardware is not yet fully available. This decouples essential parts of development from delivery times and reduces waiting periods.

At the same time, errors can be detected much earlier. Instead of extensive troubleshooting during real commissioning, reproducible test scenarios, clear status images, and a reliable basis for diagnosis and optimization are created. Coordination between mechanics, process, software, and electrics also becomes easier when all parties involved work with a consistent model.

Another advantage lies in the predictability of debugging. Changes become more traceable, tests repeatable, and relationships more transparent. This reduces the amount of on-site improvisation, and real commissioning is better prepared.

With NexaTwin, this approach can be implemented across manufacturers. The solution has a modular design and is compatible with common control systems such as Siemens, Allen-Bradley/Rockwell, Beckhoff, or CODESYS. Connections to VRC and robot environments, for example from FANUC, KUKA, ABB, or Yaskawa, can also be integrated into corresponding project contexts. This modular design keeps the approach scalable, from smaller applications to complex plant structures.

In addition, NexaCode helps to standardize recurring basic functions such as I/O, alarms, and diagnostics. It is precisely in these areas that many inconsistencies arise, which later lead to unnecessary loops in commissioning.

For companies, the greatest added value lies in the economic impact. If problems are identified earlier, the costs of any changes decrease. On-site times can be reduced, coordination becomes more targeted, and unplanned project extensions occur less frequently.

Furthermore, predictability improves throughout the entire project. Engineering, testing, training, and commissioning can be more cleanly decoupled and prepared in a more structured manner. This not only relieves project teams but also reduces risks during particularly sensitive phases with the customer.

This is crucial, especially for more complex systems: not every delay can be avoided, but many of the typical time-wasters can be identified much earlier and thus handled more affordably, quickly, and controllably.