CC-Link IE Field to EtherCAT Gateway for Mitsubishi Servo Alarm Communication

In modern manufacturing, integrating legacy fieldbus systems with high-speed industrial Ethernet protocols is a common challenge. This article presents a real-world case where a CC-Link IE Field Basic network controlling Mitsubishi servo drives was seamlessly connected to an EtherCAT-based PLC, enabling centralized alarm handling and motion control without replacing existing hardware.

Project Background

A precision electromechanical workshop in East China expanded its production line with three gantry machining modules, each equipped with eight Mitsubishi MELSERVO-J5 servo drives (MR-J5-10A-UN). These drives communicate exclusively via CC-Link IE Field Basic. The existing main controller was a Mitsubishi MELSEC iQ-R series PLC (R04CPU), which had been reliably running 14 remote I/O stations and four FR-E800 inverters over a 4 ms cycle.

However, the central SCADA system had been migrated to an Inovance AC800 series PLC (AC801-1608-TCP) using EtherCAT as the master protocol, requiring 1 ms synchronization with less than 50 ns jitter. Replacing the R04CPU with an EtherCAT master would have meant revalidating over 200 function blocks, causing two weeks of downtime and costing more than 800,000 RMB. The solution was to deploy a protocol conversion gateway that acts as a CC-Link IE Field Basic master to control the Mitsubishi servos while simultaneously operating as an EtherCAT slave to the Inovance PLC.

Key Equipment

Network Topology and Wiring

CC-Link IE Field Basic Side

The gateway’s Port 1 (RJ45) connects to the Hirschmann switch, which links to the CN11 port of each MR-J5 drive. The topology is a bus with station numbers 1 to 24. Each station exchanges 256 bytes of input and 256 bytes of output, totaling 6 kB of cyclic data. The refresh cycle is set to 1 ms, and the gateway automatically broadcasts refresh frames to maintain real-time following of the servo’s 16 kHz current loop and 4 kHz speed loop.

EtherCAT Side

Port 2 (EtherCAT IN) of the gateway connects to Port 0 of the AC801 PLC. The topology is linear, using DC-Sync mode with a measured distributed clock jitter of only 18 ns. Process data objects (PDOs) are mapped as follows: RxPDO includes control word (6040h), target position (607Ah), and target speed (60FFh); TxPDO includes status word (6041h), actual position (6064h), and actual current (6077h).

Electrical Installation

The gateway is mounted on a DIN rail, powered by 24 VDC ±5% with a maximum power consumption of 3.5 W. Power cables and EtherCAT shielded twisted pairs are routed in separate ducts, with grounding resistance below 1 Ω. During a 50 kW repeated start/stop test conducted 0.5 m from an inverter, zero communication packet loss was observed, meeting IEC 61000-4-2 Level 4 requirements.

Gateway Configuration

Hardware Initialization

After power-up, press and hold the “SET” button for 5 seconds until the RUN LED flashes rapidly, indicating maintenance mode. Set the PC network adapter to 192.168.1.10 and access the gateway’s web interface at 192.168.1.11. Import the latest ESI file (YC-CCLKIEM-ECT_V237.xml).

CC-Link IE Field Basic Master Settings

Configure the protocol version as CCLKIEFB Basic V1.10. Set the number of slave stations to 24, each mapped with 256 bytes of I/O, consuming 48 kB/s of bus bandwidth. The scan list assigns stations 1–24 to axes 1–24, matching the rotary switch S1 settings on the MR-J5 drives. If a station disconnects, the gateway automatically fills zeros and sends an alarm word 16#EE01 to the EtherCAT side, allowing the AC801 to trigger a safety function block promptly.

EtherCAT Slave Configuration

Set the synchronization cycle to 1 ms with a shift time of 250 µs. The PDO length is 48 bytes for inputs (24 × 2-byte status words + 24 × 2-byte reserved) and 48 bytes for outputs (24 × 2-byte control words + 24 × 2-byte reserved). Enable distributed clocks (DC) with a jitter tolerance of ±50 ns. The state machine supports automatic degradation from OP to Safe-OP to Init, with a reconnection time of less than 30 ms.

Data Mapping

In the YC-GateConfig “Memory Map” window, drag and drop to bind the CC-Link IE Field Basic D area with EtherCAT PDOs. For example, R0–R23 correspond to target positions for 24 axes (D3000–D3023), and T0–T23 correspond to actual positions (D4000–D4023). After downloading, the gateway restarts, the RUN LED turns solid green, and all 24 axes enter OP state on the AC801 side.

PLC Programming

Mitsubishi Side (GX Works3)

The existing positioning function block “MC_MoveAbsolute_J5” is retained. Only the “PositionCommand” for axes 1–24 is bound to D3000 + axis number, requiring no logic modifications.

Inovance Side (InoProShop)

Create an axis group “G1” and use the “InoMotionSingleAxis” library to map PDOs to %IW0–%IW47 and %QW0–%QW47. The main 1 ms loop calls 24 instances with a position loop gain Kp of 60 and a feedforward gain Kv of 60%, matching the internal gains of the MR-J5. When bit 3 of the EtherCAT status word is set, a “GroupStop” is immediately triggered, decelerating all axes to zero within 50 ms.

Data Alignment

Since both CC-Link IE Field Basic and EtherCAT operate on a 1 ms cycle, the gateway uses a “frame tail alignment” strategy to ensure data delay is less than 1 ms. Measured maximum synchronization error across 24 axes was 0.02 mm, well within the ±0.1 mm process requirement.

Commissioning and Performance Validation

No-Load Testing

All 24 axes homed simultaneously using CiA402 method 17 (home + Z pulse) at a speed of 20 mm/s and creep speed of 2 mm/s, completing in 3.8 seconds. Single-axis reciprocating motion over 300 mm with 0.5 g acceleration/deceleration achieved positioning error within ±0.015 mm.

Full-Load Testing

Machining aluminum alloy phone frames at a cycle rate of 28 pieces per minute, the system ran continuously for 96 hours. Results showed zero packet loss on CC-Link IE Field Basic, EtherCAT synchronization jitter of 18 ns, and product yield improved from 96.7% to 99.4%, reducing daily defective output by 180 pieces.

Fault Simulation

When the network cable of axis 12 was disconnected, the gateway wrote the alarm word to D4023 within 15 ms, and the AC801 immediately stopped without causing tooling collision. After reconnecting the cable, the axis came back online automatically in 30 ms without needing to re-home.

Project Summary

By using the YC-CCLKIEM-ECT protocol gateway, the user completed hardware installation in three days and software commissioning in two days, bringing the entire production line online ten days ahead of schedule. This generated direct economic benefits of over 3 million RMB. The workshop plans to integrate six additional older pulse-train servo lines into the Inovance EtherCAT master using the same gateway model, achieving a unified digital network across the shop floor.

Key Takeaway: Protocol gateways offer a cost-effective path to modernize industrial networks without discarding existing investments. This case demonstrates how a CC-Link IE Field to EtherCAT gateway can enable high-performance multi-axis control and alarm communication, ensuring seamless data exchange between different ecosystems.