Using Programmable Logic Controllers (PLCs) can be attractive in the initial stages of industrial product development. Compared to the elements of custom-embedded firmware, the ease of programming a PLC enables rapid on-site design modifications. PLCs can offer a robust off-the-shelf solution right out of the gate, with a reliability record supported by industry giants such as Allen-Bradley, Honeywell, and Rockwell. Their basic features ensure adaptability in the early product lifecycle, enabling engineers to shift product design based on customer feedback and shifting market trends. And for really low-volume annual product quantities in the 10s or 20s, there may never be a need to consider a custom solution.  

The Need for Transitioning to Custom Control PCB

While it's clear that Programmable Logic Controllers (PLCs) have some great benefits, there's more to consider. Over time, the costs and complexity of PLCs often impact the product's bottom line. PLCs can be helpful in industrial applications, but the total cost of all those features and overhead can affect an established product's profitability.  

One of our customers spent $10,000 each on Allen-Bradley PLCs to control the mixing of industrial materials in 50 rigs per year, costing $500,000 annually. Developing a custom printed circuit board with embedded control components has reduced this line-item cost per rig to sub-$1,500, resulting in $425,000 in annual savings after development investment.  

Another example? A company used a $1500 Panasonic PLC to produce 500-600 annual units of their flagship product. By shifting to a custom PCBA control board and UI display, future savings could add up to $544,500 per year.  

The Hidden Costs of PLCs in Established Products 

When we look at product profitability from a broader perspective, particularly while evaluating the continued use of PLCs in established products, the benefits soon fade when manufacturing, supply chain management, and production scaling begin to take on greater importance.

During the initial stages of new product development, businesses often consider the associated costs of adopting PLCs as essential investments for prototyping, testing, and fine-tuning. However, as products become established in the market, several costs related to PLCs can become "hidden" or overlooked. These costs, while not immediately apparent, can erode profitability over time. Here's how these costs can manifest as hidden expenses in established products.  

1. Complacency with Existing Components: Once a product is established, there's a tendency to adopt a "if it isn't broken, don't fix it" mindset. This can lead to overlooking ongoing costs associated with maintaining and operating PLCs, as they become part of the 'standard' operating expenses. 
2. Over-Featured Systems: While the multitude of PLC features are seen as assets in the early stages of a project, they can become redundant as the product stabilizes and matures. The expenses tied to these unnecessary features often go unnoticed and unexamined. 
3. Maintenance and Report: PLCs are reliable, but maintenance of older systems is costly. Components such as connectors, relays, and power supplies may require replacement. Likewise, protective casings, air filters, and cooling systems may need regular checks. These ongoing costs, essential for ensuring smooth operations of established products, can eat into profit margins. 
4. Inefficiencies in Scalability: As production volume grows, PLC-related costs can surge, especially without the benefits of bulk discounts or economies of scale. And their point-to-point wiring can dramatically add to assembly labor costs and mistakes.
5. Vendor Dependency: Over-reliance on a specific PLC vendor or system can lead to unforeseen costs if the vendor discontinues a product, rolls out an incompatible upgrade, or changes their pricing structure. 
6. Opportunity Costs: Staying with a PLC system for an established product might mean missing out on innovations or more cost-effective solutions that have emerged since the product's inception. The cost of not switching or upgrading can be a significant hidden drain on resources. 
7. Inventory Carrying Costs: Companies may keep a stock of PLCs or related components as spares for established products to ensure part availability. Over time, certain models might become obsolete or harder to source, leading to increased costs or even production delays. The costs associated with storing and managing this inventory — especially if the parts become obsolete or are overstocked — can be a hidden expense.
8. Security: PLCs generally operate on closed systems with limited security, while embedded controllers' diverse connectivity can expose them to more threats. The security differences stem from their operating systems, connectivity, and vulnerability management. Proactive understanding and addressing of each system's unique security challenges are crucial.
9. Version Controls: In plant automation, PLC programs can be quickly altered for immediate needs, whereas volume production emphasizes uniform firmware releases. While board swaps simplify troubleshooting in production, this isn't feasible with PLCs.
10. Connectivity: For connectivity, PLCs ensure seamless integration with industrial networks, while custom PCBs offer adaptable solutions. The choice hinges on specific connectivity and integration needs.

Custom Control PCB Solutions: The Future of Cost Efficiency 

Custom control Printed Circuit Boards (PCBs) are specially designed to meet the needs of their individual applications, allowing businesses to reduce costs by investing only in the essential capabilities relevant to their product or operations. Such precision in design not only removes redundant features but also guarantees optimal efficiency. For this reason, custom control PCBs are well suited and optimized to the particular tasks and conditions they are meant for, boosting their performance and durability. Likewise, removing these redundancies also contributes to significant cost savings for established products over their entire lifecycle. 

Steps for Transitioning from PLC to Custom PCB 

A successful transition from PLCs to custom control PCBs requires a clear understanding of the development process and the up-front costs needed to achieve impressive cost-efficiencies and savings over the product's life. Developing a fully functional custom control PCB requires thorough planning, specialized knowledge, and precision. This process typically spans 1 to 2 years, including idea conceptualization, accurate documentation, and drafting of a detailed Request for Proposal (RFP).

While evaluating the development timeline, here are the critical milestones that your organization should anticipate: 

• Gathering Requirements: This is the initial phase for idea conceptualization, planning, documentation, and the drafting of a detailed Request for Proposal (RFP). 
• Prototyping: Used in various forms to check the progress of key parts of the product system or the whole system in general. Plan on several prototype versions depending on your product.  
• Bench Testing: This is the foundational phase where the preliminary design of the PCB is tested under controlled conditions. Here, the primary goal is to ensure that the essential functions of the design operate as intended and to identify any immediate flaws or inefficiencies. 
• Iterating: The design undergoes multiple iterations based on feedback and results from the prototyping stage. Adjustments, optimizations, and refinements are made to enhance performance, reliability, and efficiency. 
• Field Testing or Key Customer Testing: Once a stable prototype is developed, it's subjected to real-world conditions or handed over to key customers for testing. This phase provides invaluable insights into how the PCB performs in its intended environment and gathers user feedback. 
• Certifying: Depending on the application and industry, the PCB may need to meet specific standards or regulations. The certifying phase ensures the product is compliant, safe, and reliable for its intended use. 
• Design for Manufacturing / Transferring to Production: The design is finalized and optimized for mass production. This stage is completed together with a customer’s chosen contract manufacturer (CM) to ensure a seamless transition from prototype to large-scale manufacturing while maintaining quality and efficiency. 
• Production Testing Requirements Development: As the PCB enters the production phase, specific testing protocols are developed to ensure each unit meets the set quality and performance standards. 
• Parallel Accelerated Life Testing: In this phase, the PCB is subjected to stress conditions to simulate its lifespan and determine its longevity 

Key Considerations for a Successful Transition to Custom Control PCBs 

Transitioning to custom control PCBs is a significant leap in technology and efficiency for many businesses. While the advantages of custom PCBs are unmistakable, the transition requires considerable planning and foresight. 

• Detailed Engineering Requirements Document: Starting with a comprehensive engineering requirements document is crucial for the success of the project. This document will serve as a blueprint, guiding the entire development process and ensuring that all technical and functional specifications are well-defined and aligned with your business objectives.
• Maintain Ownership of Your Intellectual Property:  It is important to ensure that you retain ownership of your software, hardware, and design files. Having complete control over your intellectual property (IP) is crucial for the current version of your product as well as its entire lifecycle, as it ensures freedom in decision-making and adaptability. Contract manufacturers (CMs) may restrict access to your software source code, mechanical design files, and the IP they are creating with you on your project, as part of the "no NRE costs" agreement. It is important to be aware of this and take necessary steps to protect your IP. 
• Evaluate Your Engineering Team: The software engineering and control group can play a pivotal role in a successful product transition. Assessing interest and willingness to transition is crucial for long-term success. Can your PLC programmers shift to embedded software? Often, with the right training and interest, you can anticipate a successful transition. However, it's crucial to identify any skill gaps early on and address them, either through training or hiring. 
• Partner with a Credible Design Services Company: The expertise of the electronics engineering design services company you choose can make or break your transition. Ensure they have a solid track record, relevant experience, and positive client testimonials. Look for a willingness to work together with the existing product teams through this transition – it will take combined teamwork from your product experts and a knowledgeable technology vendor. 
• Avoid the Temptation of the Lowest Bidder: While cost-efficiency is essential, the cheapest option is not always the best. Especially when it comes to owning your product's intellectual property (IP). Prioritize quality, expertise, and reliability over mere cost savings.  It may seem like Contract Manufacturers are offering "free" NRE, but in reality, it can be a bit misleading. 
• Identify a Reliable Contract Manufacturer: Once your custom PCB design is ready, the next step is to find a reliable contract manufacturer that can cater to your specific volume needs. Whether you need tens of thousands of PCBs per year or a lower number, the CM you choose must be equipped to handle the job. It's important to note that not all CMs are the same, and their expertise is critical in ensuring the mass production of high-quality PCBs. Sometimes, contract manufacturers try to fit your project into a pre-existing solution, which may not be the best fit for your needs. 
• Plan for Future Expansion and Hardware Considerations: When drafting your Request for Proposal (RFP), it's wise to anticipate potential future product features and hardware scalability. Investing a bit more initially in expansion electronics hardware can save significant time, money, and future re-work. A quality engineering consultant group can assist in striking the optimal balance between current requirements, product profitability, and long-term goals. 
• Expect Revisions: Developing printed circuit boards (PCBs) is a rigorous process that greatly benefits from close collaboration with your sales and product management teams. As with any product development, constantly striving for improvement through iterations and revisions is a hallmark of excellence. Flexibility and adaptability are critical attributes that will drive the future evolution of your product.