How Bad PLC Programming Costs You: Lost Revenue, Safety Issues, and More

Programmable logic controllers (PLCs) have become foundational components in industrial facilities. They control manufacturing processes, assembly lines, safety systems, and more. These compact industrial computers automate tasks that range from basic to highly complex. It is no surprise that the market for PLCs is estimated to be valued at $15.5 billion by 2026.

With industries increasingly relying on PLCs as a core part of operations, poorly written PLC code can result in major costs through production downtime, regulatory fines, lack of flexibility to add capabilities, and overall inefficient performance.

What is Bad PLC Programming?

Bad PLC programming can take several forms. It can be code that is buggy, difficult to interpret, ignores best practices, lacks appropriate testing, or fails to program adequate alarms and safety checks. This includes:

  • Bugs that cause downtime or malfunctions: All code will have defects, but sloppy PLC programming often contains bugs that halt or impair processes when triggered, requiring downtime to correct.
  • Code that is hard to understand or maintain: Programming lacks consistency, commenting for logic, and clear labeling or tagging. This makes the code difficult to troubleshoot or build upon later.
  • Not following best practices: Failing to follow industry conventions for organization, naming, formatting, modularization, and documentation.
  • Lacking safety checks and alarms: Safety interlocks, limit switches, and alarms may not be implemented or thoroughly tested—putting assets and workers at risk.
  • Inadequate testing: Code is not rigorously stepped through with simulation and test cases to catch errors pre-commissioning.

Quite simply, bad PLC programming puts your operation and your employees at risk.

Lost Revenue from Downtime
Unplanned downtime caused by PLC programming issues can create significant losses. Unplanned downtime in manufacturing can add up to as much as $260,000 an hour depending on process complexity and industry.

Full process outages or stoppages have the highest cost impact, but even intermittent faults or poor performance from bad code can substantially impact performance—creating scrapped product batches, missed customer deadlines, or added production steps to compensate. Repairing PLC issues requires technicians to drill into faulty code or even replace control hardware in severe cases.

While any one incident traced to PLC coding errors may seem small, the cumulative loss across months and years can ultimately amount to a significant drain on bottom-line production capacity.

Safety and Regulatory Issues

In industrial settings, worker safety is essential. However, PLCs lacking appropriate safeguards and interlocks integrated into their programming put employees at risk for injury around heavy machinery, robotic equipment, hazardous chemicals, and other assets. These incidents lead not only to direct medical or legal costs, but also regulatory fines.

Regulatory agencies like OSHA mandate safety requirements and levy steep per-incident penalties for violations that can be traced to safety procedure lapses.

Even absent direct injuries, process upsets or accidents damaging assets can trigger inspections inviting fines. In more regulated industries like energy, pharmaceuticals, and chemicals, programming errors that result in unsafe conditions or loss of containment draw strict sanctions. Fines easily scale into six figures depending on severity.

Other Costs

In addition to overt equipment failures and safety repercussions, poor-quality PLC code inflicts less visible but still substantial long-term costs through inefficiency, lack of agility to make changes, and difficulty troubleshooting root causes when abnormal conditions occur. A PLC programmer who writes “bad code” can create suboptimal systems, such as:

  • Hard to troubleshoot or update: Cryptic logic flow, lack of commenting, and disorganization all hurt diagnosing faults or adapting programming down the road. This directly translates to excess technician labor hours whenever issues arise.
  • Inflexibility for new capabilities: Modern processes benefit from continually adding sensors, analytics, and updated control schemes. Hardcoded logic that is expensive to replace makes this impractical to implement.
  • Difficulty tracing root causes: When product quality, raw material consumption, or other metrics drift out of spec, analyzing poorly documented code logic to uncover why becomes extremely tedious.
  • Higher maintenance costs: Beyond direct downtime losses, badly coded PLC systems have higher operating, maintenance, and troubleshooting needs.

While downtime creates substantial problems, chronic issues from subpar programming can hurt productivity and weigh on the bottom line.

You Need Experienced, Innovative PLC Programmers

Solid PLC programming is crucial as a foundation. When done poorly—reflecting shortcuts, lack of rigor, or outdated methods—problems arise. Organizations must recognize PLC coding expertise as a strategic imperative, not just a rote task. With industries increasingly relying on automated processes and controls, the quality of the PLC programmer you hire directly affects the bottom line.

Pacific Blue Engineering has expert PLC programmers to ensure robust and reliable controls automation for your environment. We deliver engineering consulting and controls system integration for custom automation solutions, legacy control modernization, and functional safety services for the most demanding projects.

Contact Pacific Blue Engineering today at (657) 201-8603 or request a consultation online.