EtherNet/IP to SPI Embedded Board Enables Compact Communication Integration in Industrial Robots
Time:2026-08-24 Browse: 0
Meta Description: A WL-EIP-SPI embedded EtherNet/IP to SPI communication board connects a Rockwell EtherNet/IP PLC with SPI-based robot controllers, encoders, ADC modules, Flash memory, and OLED displays.
Keywords: EtherNet/IP to SPI, EtherNet/IP gateway, SPI communication, embedded communication board, industrial robot, collaborative robot, Rockwell PLC, Micro870, industrial automation, robot control system
Embedded EtherNet/IP to SPI Communication for Industrial Robot Integration
Industrial robots increasingly rely on compact electronic control architectures. Motion controllers, absolute encoders, ADC modules, memory devices, displays, and other embedded peripherals are often connected through SPI because of its simple hardware architecture and high communication efficiency.
However, SPI-based embedded devices normally do not provide a native industrial Ethernet interface.
This creates an integration challenge when a robot needs to communicate with a Rockwell Automation EtherNet/IP PLC.
A recent industrial robot integration project used a WL-EIP-SPI EtherNet/IP to SPI embedded communication board from WENLIAN Technology to solve this problem.
The compact communication board was installed directly inside the robot arm's electrical enclosure, creating a bidirectional communication path between the EtherNet/IP PLC master and multiple SPI peripherals.
The resulting architecture connects the control cabinet to the robot's internal electronics without requiring a conventional external protocol gateway.
Application Background
The application involved a six-axis collaborative robot.
The robot's internal FPGA motion controller, multi-turn encoders, ADC acquisition module, SPI Flash memory, and OLED display all communicated through SPI.
Because the internal electronics did not provide an Ethernet interface, the robot could not directly communicate with the EtherNet/IP master in the control cabinet.
A conventional external gateway could provide protocol conversion, but it would introduce additional wiring, consume cabinet space, and create another external device that would need to be installed and maintained.
The engineering team therefore selected an embedded EtherNet/IP to SPI communication solution.
The communication board was integrated into the robot's forearm electrical compartment, allowing the protocol conversion function to become part of the robot's internal electronics architecture.
The resulting communication path was:
Rockwell EtherNet/IP PLC → Industrial Ethernet Switch → WL-EIP-SPI Embedded Board → SPI Devices
The link supports bidirectional data exchange.
Motion commands can be transmitted from the PLC to the robot controller, while position, temperature, load, and fault information can be returned from the robot to the PLC.
System Architecture and Hardware Configuration
The system uses a Rockwell Automation Micro870 PLC as the EtherNet/IP master.
The PLC communicates with the embedded WL-EIP-SPI board through an industrial Ethernet switch.
The embedded board provides two independent hardware SPI master channels.
The first SPI channel, SPI0, is connected to the FPGA motion controller and multi-turn absolute encoders.
The second channel, SPI1, connects to the ADC acquisition module, SPI Flash storage, and OLED status display.
This separation allows different SPI peripherals to operate with their own communication timing requirements.
The selected WL-EIP-SPI embedded board was designed for applications where installation space is limited.
The board integrates an EtherNet/IP CIP protocol stack and provides two 3.3 V hardware SPI master interfaces.
It also includes ESD and pulse-group protection for industrial environments.
The board operates from a standard 24 V DC industrial power supply and provides indicators for power, Ethernet link, data transmission and reception, and fault status.
These features simplify commissioning and troubleshooting during robot system integration.
Mechanical Installation Inside the Robot
The embedded communication board was installed inside the sealed electrical compartment of the robot forearm.
Insulating nylon standoffs were used to secure the board mechanically.
The installation position was selected away from servo power cables to reduce the influence of electromagnetic interference generated by motors, drives, contactors, and other high-power components.
The shielded Ethernet cable was routed through the robot's hollow arm structure and connected to the industrial Ethernet switch in the control cabinet.
SPI communication cables were kept as short as practical.
Shielded twisted-pair wiring was used to improve signal integrity in the compact robot enclosure.
The communication devices were also connected to a common reference ground to reduce potential differences that could otherwise affect communication stability.
This wiring strategy is particularly important for robotic systems because communication cables and motor power cables often need to share a limited physical space.
EtherNet/IP Network Configuration
The PLC, embedded communication board, and engineering computer were connected to the same local Ethernet network during commissioning.
The network configuration used a static IP arrangement.
The Micro870 PLC was assigned the address 192.168.1.10, while the embedded EtherNet/IP to SPI board used 192.168.1.30.
The subnet mask was configured as 255.255.255.0.
Automatic reconnection and link heartbeat monitoring were enabled.
After the configuration was downloaded and the communication board restarted, network connectivity was verified through ping testing.
The EtherNet/IP communication architecture primarily uses cyclic implicit I/O messaging, with explicit messaging available for configuration and other communication requirements.
The configured RPI was 8 ms.
A bidirectional 64-byte data mapping area was established between the PLC and the embedded board.
The downstream data included motion-related information such as position commands, speed parameters, and acceleration/deceleration settings.
The upstream data included joint angle information, servo temperature, load status, and fault codes.
The corresponding EDS file allows the communication device to be recognized and configured within the Rockwell Automation engineering environment.
Independent SPI Communication Channels
The two SPI channels were configured independently to accommodate different peripheral requirements.
SPI0 operated at an 8 MHz clock frequency with CPOL = 1 and CPHA = 0.
This channel was used for higher-speed communication with the FPGA controller and encoder devices.
SPI1 operated at 1 MHz with CPOL = 0 and CPHA = 1.
This channel was used for lower-speed data acquisition, Flash memory, and OLED display functions.
SPI byte-level CRC checking was enabled to improve data integrity.
This configuration was particularly relevant to the robot application because servo motors, contactors, and switching devices can generate electromagnetic interference during operation.
Separating the SPI channels also avoids forcing all connected peripherals to operate under the same timing parameters.
Motion Control and Communication Testing
The integrated system was tested using single-axis motion commands, multi-axis coordinated motion, and circular trajectory programs.
Commands generated by the Micro870 PLC were transferred through EtherNet/IP to the embedded communication board.
The board then converted the Ethernet-based data into SPI communication for the FPGA motion controller.
During testing, the robot completed 200 consecutive trajectory programs without observed communication stalls or trajectory deviation.
The measured overall transmission latency was ≤18 ms under the tested configuration.
The result demonstrated that the embedded protocol conversion architecture could support the communication requirements of the collaborative robot application.
Continuous Monitoring and Data Acquisition
The communication system was also subjected to a 72-hour continuous operating test.
During the test, joint angle information, motor temperature, and vibration-related data were continuously collected.
No abnormal data jumps or communication data loss were observed during the reported test.
When over-temperature or overload conditions occurred, the corresponding fault information could be transmitted to the PLC and used to trigger the required safety interlock logic.
The SPI interface was also used to communicate with the OLED display.
Operating parameters could therefore be displayed locally inside the robot system.
The SPI Flash interface provided a means of storing operating logs, creating an additional source of maintenance and troubleshooting information.
This combination of communication, local display, and event logging allows the embedded board to perform more than simple protocol conversion.
Signal Integrity and Reliability Verification
Signal quality was checked using an oscilloscope during SPI communication.
At the 8 MHz SPI clock frequency, the measured timing error was reported as less than 0.5 μs.
The observed signal waveform remained stable without significant abnormal noise or distortion under the tested installation conditions.
Additional reliability tests were performed to evaluate the communication system under typical industrial operating conditions.
During an Ethernet cable hot-plug test, communication was automatically restored within approximately 1 second.
The system also maintained communication during servo full-load operation without reported frame loss or data corruption.
The embedded board operated within a tested temperature range of -15°C to 60°C.
After a complete power-off and restart, the board automatically loaded its stored configuration, eliminating the need for repeated manual commissioning.
Why an Embedded Protocol Conversion Board Can Be Useful
The main advantage of this architecture is its compact physical design.
Instead of installing a conventional external gateway in the control cabinet, the protocol conversion function is integrated directly into the robot's electrical compartment.
This can reduce external wiring and free cabinet space.
For robot manufacturers, embedded communication can also simplify system-level integration.
The EtherNet/IP interface provides connectivity to the industrial control network, while the SPI interfaces communicate directly with internal electronic modules.
This creates a clear separation between the industrial network layer and the robot's internal peripheral communication layer.
Another advantage is the ability to configure different SPI channels independently.
This is useful when a robot contains devices with significantly different communication speeds, SPI modes, or data requirements.
Potential Applications Beyond Collaborative Robots
The EtherNet/IP to SPI embedded architecture is not limited to six-axis collaborative robots.
Similar requirements can occur in other industrial equipment where internal electronics communicate through SPI while the machine needs to connect to an industrial Ethernet controller.
Potential applications include robotic manipulators, automated handling equipment, AGV vehicle controllers, machine vision peripherals, embedded motion-control systems, industrial measurement equipment, and other compact automation devices.
For equipment manufacturers, an embedded communication board can provide an alternative to installing a separate external protocol gateway when physical space, wiring complexity, and system integration are important considerations.
Integration Considerations for OEM Equipment
When implementing an EtherNet/IP to SPI solution in an industrial product, engineers should evaluate more than protocol compatibility.
The physical installation environment is equally important.
SPI wiring should be kept short where possible, particularly at higher clock frequencies.
Communication cables should be routed carefully around servo and motor power wiring.
Grounding and shielding should be considered as part of the overall electrical design.
The required SPI mode and clock frequency should also be matched to the connected peripheral devices.
On the EtherNet/IP side, the PLC data mapping, RPI configuration, EDS integration, watchdog behavior, and fault-handling strategy should be defined before commissioning.
For equipment intended for mass production, the communication solution should also be evaluated for repeatability, configuration retention, temperature performance, electromagnetic compatibility, and maintenance requirements.
Conclusion
The WL-EIP-SPI embedded EtherNet/IP to SPI communication solution provides a compact approach for integrating SPI-based robot electronics with an industrial EtherNet/IP control network.
In this collaborative robot application, a Rockwell Micro870 PLC communicated with internal FPGA control electronics, absolute encoders, ADC modules, SPI Flash memory, and an OLED display through a single embedded protocol conversion platform.
The tested configuration achieved an 8 ms EtherNet/IP RPI, dual SPI channels, 8 MHz and 1 MHz SPI communication, 64-byte bidirectional data mapping, and reported communication latency of 18 ms or less.
The 72-hour continuous test, Ethernet reconnection test, servo full-load operation, and -15°C to 60°C temperature verification further demonstrated the stability of the tested implementation.
For industrial robot and automation equipment manufacturers, the approach provides a practical option when internal electronics use SPI but the complete machine needs to communicate with a Rockwell EtherNet/IP PLC network.
More importantly, the embedded architecture can reduce external gateway hardware, simplify wiring, save installation space, and make protocol conversion part of the machine's own electrical design.
For compact industrial equipment, integrating communication directly into the machine can be an effective way to bridge the gap between embedded electronics and factory-level industrial Ethernet networks.
