Introduction
In modern industrial environments, capturing reliable data from diverse operational technology (OT) sensors and integrating it seamlessly with IT infrastructure is paramount for efficiency and predictive maintenance. While off-the-shelf IoT gateways exist, they often lack the specific interface mix, environmental resilience, or processing capabilities required for demanding applications, necessitating custom-engineered solutions.
The Challenge
A client specializing in heavy machinery monitoring needed a robust Industrial IoT (IIoT) gateway capable of bridging legacy sensors with their modern cloud analytics platform. Their key challenges included:
- Diverse Sensor Integration: The gateway needed to reliably interface with existing machinery sensors using Modbus RTU over RS485, as well as various analog sensors outputting 4-20mA current loops.
- Harsh Operating Environment: The gateway would be deployed in environments with significant electrical noise (EMI), vibration, and wide temperature fluctuations. Reliability was non-negotiable.
- Data Processing & Security: Basic data aggregation and filtering were required on the edge, along with secure and reliable communication to the cloud via wired Ethernet.
- Limitations of Existing Solutions: Off-the-shelf gateways failed to meet the combination of ruggedness, specific I/O requirements, and desired processing headroom for future features.
The client required a partner with deep expertise in both rugged hardware design and low-level Linux software development to create a tailored, reliable solution.
The Solution: Integrated Hardware and Software Expertise by Onplick
Onplick undertook the development of a custom IIoT gateway, delivering a complete solution from concept through to production-ready design. Our approach focused on tightly integrating bespoke hardware engineering with custom Linux driver and Board Support Package (BSP) development.
Implementation: Hardware Design
Our hardware team designed a custom PCB engineered for reliability and performance in harsh industrial settings:
- System-on-Chip (SoC) Selection: An NXP i.MX 8M Mini processor was chosen for its balance of processing power, industrial temperature range support, and peripheral integration capabilities.
- Isolated Communication Interfaces: A galvanically isolated RS485 transceiver circuit was implemented to ensure robust Modbus communication and protect the system from ground loops and electrical surges common in industrial plants. High-quality components and careful layout techniques were employed to maintain signal integrity.
- Precision Analog Front-End: A dedicated analog front-end using precision operational amplifiers and a multi-channel Analog-to-Digital Converter (ADC) was designed to accurately measure the 4-20mA signals, including filtering and protection circuitry.
- Robust Power Supply: A wide-input range DC-DC power supply was designed with filtering and transient voltage suppression to handle noisy industrial power rails.
- EMC/EMI Mitigation: Significant attention was paid to EMC/EMI compliance throughout the design process. Techniques included optimized PCB layer stackup, strategic ground planes, controlled impedance routing, shielding, and careful component placement to minimize emissions and maximize immunity.
- Thermal Management: A thermal design was implemented considering the SoC power dissipation and industrial temperature requirements, potentially involving heatsinking or enclosure airflow considerations.
Implementation: Linux Driver Development & BSP Customization
Parallel to the hardware design, our software team developed the necessary Linux drivers and customized the BSP:
- Custom RS485 Driver: While the Linux kernel provides serial drivers, a custom layer was developed to handle the specific timing requirements, half-duplex control for the RS485 transceiver, and potentially integrate parts of the Modbus RTU protocol handling for efficiency.
- ADC Driver & Calibration: A custom IIO framework driver was developed for the specific ADC, enabling precise control over sampling rates, channel configuration, and integration of calibration data stored in non-volatile memory for improved accuracy across temperature ranges.
- Device Tree Configuration: The device tree was meticulously configured to accurately describe the custom hardware, including GPIO assignments for interface controls, interrupt routing, clock configurations, and peripheral connections (I2C, SPI for onboard sensors/peripherals).
- BSP Integration: The Yocto Project was used to build a lean, customized Linux distribution containing only necessary components, optimizing boot time and resource usage. Secure boot features available on the i.MX 8M Mini were configured to enhance system integrity.
- Network & Application Layer Support: Standard Linux networking stack was configured and tested for reliable Ethernet communication. Libraries and APIs were provided to the client’s application development team for easy access to the sensor data collected by the custom drivers.
Results
The custom IIoT gateway developed by Onplick successfully met and exceeded the client’s requirements:
- Reliable Multi-Sensor Integration: The gateway seamlessly collected data from both legacy RS485 Modbus devices and analog sensors simultaneously.
- Proven Environmental Resilience: The hardware passed rigorous environmental and EMC testing, proving its suitability for deployment in demanding industrial conditions.
- Stable & Secure Data Transmission: The tailored Linux system provided a stable platform for edge processing and reliable, secure data forwarding to the client’s cloud platform.
- Future-Proof Platform: The chosen SoC and custom design provided performance headroom for future feature additions, such as additional sensor types or more complex edge analytics.
- Accelerated Deployment: By providing an integrated, validated hardware and software solution, Onplick significantly reduced the client’s integration effort and time-to-market for their enhanced monitoring system.
Conclusion
This project demonstrates Onplick’s capability to deliver highly specialized embedded systems by combining expert hardware design with tailored Linux driver and BSP development. By addressing the unique challenges of industrial environments and legacy system integration, we enabled our client to deploy a robust, reliable, and future-proof IIoT solution.
