Ethernet/IP to CANopen Gateway for Precision Injection Molding

In high-precision injection molding, a single production line often mixes devices from different vendors, each speaking its own industrial protocol. A Rockwell PLC using Ethernet/IP might need to command a servo drive that only understands CANopen. Without a bridge, these devices remain isolated, forcing costly hardware swaps or complex custom integrations. A dedicated protocol gateway solves this by translating commands in real time, enabling seamless coordination and unlocking the full potential of both systems.

The Communication Challenge in Modern Injection Molding

Precision injection molding demands tight synchronization between the machine’s clamping unit, injection screw, and ejector. Servo drives execute these movements with micron-level accuracy, often controlled by a central PLC. However, when the PLC uses Ethernet/IP (common in Rockwell Automation architectures) and the servo drive uses CANopen (widely adopted by drive manufacturers like Inovance), direct communication is impossible. This protocol mismatch creates data silos, limits real-time performance, and complicates machine upgrades.

A protocol conversion gateway acts as a real-time interpreter. It maps Ethernet/IP assemblies to CANopen Process Data Objects (PDOs) and Service Data Objects (SDOs), allowing the PLC to read drive status, write position setpoints, and adjust parameters as if the servo were a native Ethernet/IP device. This approach preserves existing hardware investments and reduces engineering time.

Typical Servo Drive Capabilities (Example: IS620PT Series)

Modern CANopen servo drives offer exceptional performance for injection molding applications. Consider these representative specifications:

Note: Specifications are typical for high-performance servo drives used in injection molding. Actual values may vary by model and configuration.

How the Gateway Delivers Real-Time Control

The gateway’s core function is to maintain determinism while converting protocols. It achieves this through several mechanisms:

• ✓ Sub-millisecond latency: Internal processing delay is kept below 1 ms, ensuring that position commands from the PLC reach the drive within the same control cycle. This is critical for high-speed injection phases where timing errors cause defects.
• ✓ PDO mapping flexibility: Users can map Ethernet/IP input/output assemblies directly to CANopen RPDOs and TPDOs. For example, the PLC’s output assembly might contain target position and control word, while the input assembly carries actual position and status word.
• ✓ SDO access for parameters: Configuration data like acceleration ramps or PID gains can be read/written via explicit messaging, allowing the PLC to adapt drive behavior on the fly for different mold setups.
• ✓ Heartbeat and node guarding: The gateway monitors CANopen node status and reports faults to the PLC, enabling quick recovery from communication drops.

Simplified Configuration in Four Steps

Modern gateways offer web-based configuration tools that eliminate the need for complex scripting. A typical setup process involves:

Industrial-Grade Reliability for 24/7 Operation

Injection molding facilities often run continuous production. The gateway must withstand harsh electrical environments. Key design features include:

• Dual power inputs (typically 24 V DC) with reverse polarity protection
• Galvanic isolation between Ethernet and CAN interfaces (usually 1500 V DC)
• Wide operating temperature range (-40°C to +75°C)
• Metal housing with DIN-rail mounting for secure installation inside control cabinets
• EMC compliance according to IEC 61000-6-2 (industrial immunity) and IEC 61000-6-4 (emission)

These characteristics ensure stable communication even near variable frequency drives or high-current switching devices common in molding machines.

Flexible Manufacturing Without Hardware Changes

One of the strongest arguments for using a protocol gateway is the ability to integrate legacy or mixed-vendor equipment. When a production line needs to switch from making thin-wall containers to thick automotive parts, the PLC can simply download new servo parameters via the gateway. There is no need to rewire or replace drives. This flexibility supports:

Real-World Application: Clamping Unit Control

Consider a typical injection molding machine with a toggle clamp driven by a CANopen servo. The Rockwell PLC runs the machine sequence and sends position setpoints via Ethernet/IP. The gateway converts these to CANopen PDOs. During mold close, the drive follows a precise speed profile to avoid mold damage. Once closed, the PLC commands high torque to build clamp force. The gateway’s low latency ensures that force feedback is reported in real time, allowing the PLC to adjust injection pressure accordingly. This closed-loop control across protocols is essential for producing parts with tight tolerances.

Key Takeaways

An Ethernet/IP to CANopen gateway is more than a protocol converter—it is an enabler of precision, flexibility, and reliability in injection molding. By bridging the communication gap between Rockwell PLCs and CANopen servo drives, manufacturers can achieve:

• ▸ Micron-level positioning accuracy for consistent part quality
• ▸ Real-time synchronization with less than 1 ms delay
• ▸ Cost-effective integration of existing and new equipment
• ▸ Rugged design for continuous industrial operation

As injection molding moves toward smarter, more connected factories, such gateways will play a crucial role in harmonizing diverse automation systems.