CC-Link Protocol Tutorial 2025 | Complete Industrial Network Guide

Introduction: Mastering CC-Link Protocol for Industrial Automation in 2025

CC-Link (Control & Communication Link) protocol has established itself as the dominant industrial network standard throughout Asian markets, particularly in Japan where it originated and China where it commands over 30% market share. Developed by Mitsubishi Electric in 1996 and now maintained by the CC-Link Partner Association (CLPA) with over 3,000 member companies worldwide, CC-Link protocol provides comprehensive communication solutions ranging from high-speed motion control to enterprise-level information networks.

The CC-Link protocol family encompasses multiple variants designed for specific application requirements: classic CC-Link for fieldbus applications, CC-Link IE (Industrial Ethernet) Field Basic for cost-effective Ethernet connectivity, CC-Link IE Field for high-performance control, and CC-Link IE TSN (Time-Sensitive Networking) representing the cutting edge of deterministic Ethernet communication. This comprehensive protocol family ensures appropriate solutions across the entire industrial automation hierarchy from sensor level to enterprise integration.

This complete CC-Link protocol tutorial covers everything from fundamental network architecture to advanced implementation techniques including network configuration, Mitsubishi PLC integration, wiring practices, diagnostic procedures, and troubleshooting methods. Whether you're implementing manufacturing execution systems, building automation networks, or developing motion control applications, this guide provides the technical depth and practical knowledge required to master CC-Link communication protocol programming and system integration.

Understanding CC-Link protocol has become essential for automation engineers working with Asian-manufactured equipment or deploying systems in Asian markets where CC-Link represents the de facto industrial networking standard. The protocol's evolution toward Ethernet-based variants and TSN integration demonstrates CLPA's commitment to maintaining CC-Link relevance as Industry 4.0 and smart manufacturing requirements drive industrial communication toward higher performance, greater interoperability, and seamless IT/OT convergence.

Chapter 1: CC-Link Protocol Family Overview

What is CC-Link Protocol?

CC-Link protocol is an open industrial network system enabling communication between PLCs, remote I/O, sensors, actuators, drives, robots, and other automation devices through standardized physical layers and application protocols. The original CC-Link specification utilized dedicated serial communication hardware providing deterministic fieldbus performance, while modern Ethernet-based variants leverage standard networking infrastructure for higher bandwidth and extended connectivity options.

The CC-Link Partner Association (CLPA) maintains all CC-Link specifications as open standards, publishing detailed technical documentation freely available to manufacturers and users. This openness has driven widespread adoption, with over 19 million CC-Link devices installed globally and extensive vendor support across major automation equipment suppliers.

Key Characteristics of CC-Link Protocol:

• Multi-vendor support through open standardization
• Deterministic communication for real-time control applications
• Flexible topology supporting line, star, and ring configurations
• Extensive device profiles covering virtually all automation equipment types
• Backward compatibility maintaining investment protection during system upgrades
• Comprehensive diagnostic capabilities simplifying troubleshooting and maintenance

CC-Link Protocol Applications

Manufacturing automation represents the largest CC-Link deployment sector, with applications in automotive assembly, electronics production, food and beverage processing, pharmaceutical manufacturing, and general industrial machinery. The protocol's deterministic performance and extensive device support make it ideal for complex production lines requiring coordinated control of multiple subsystems.

Building automation systems utilize CC-Link for integrating HVAC equipment, lighting controls, access systems, and energy management devices into comprehensive facility management networks. The protocol's reliability and scalability support large commercial and industrial facilities with thousands of control points.

Process automation applications leverage CC-Link for connecting field instruments, analyzers, and control valves in chemical processing, water treatment, and power generation facilities where reliable communication under harsh environmental conditions is essential.

Motion control systems implement CC-Link for coordinating multiple servo drives, robots, and positioning systems in packaging machinery, material handling equipment, and machine tools where precise synchronization and fast update rates are critical.

CC-Link Protocol Family Variants

CC-Link (Classic Fieldbus)

The original CC-Link specification provides deterministic fieldbus communication at speeds from 156 kbps to 10 Mbps over dedicated RS-485 physical layer. Supporting up to 64 stations with maximum cable lengths varying based on communication speed (1,200 meters at 156 kbps down to 100 meters at 10 Mbps), classic CC-Link continues serving applications requiring proven reliability and compatibility with existing installations.

Classic CC-Link supports four station types: master stations controlling network communication, local stations providing simple remote I/O functionality, remote device stations connecting individual sensors and actuators, and intelligent device stations implementing sophisticated device-level processing. This hierarchical approach simplifies network design while supporting diverse application requirements.

CC-Link IE (Industrial Ethernet) Field Basic

CC-Link IE Field Basic provides cost-effective migration to Ethernet-based communication while maintaining compatibility with existing CC-Link concepts and programming models. Operating at 100 Mbps over standard Ethernet physical layer, this variant enables simple network construction using commercial switches and standard RJ45 connectors.

The Field Basic specification supports up to 64 stations per network with extensive data capacity (2,048 bytes cyclic data per station) enabling complex device integration without multiple network segments. This variant suits applications transitioning from fieldbus to Ethernet where high-speed motion control isn't required but Ethernet infrastructure benefits are desired.

CC-Link IE Field

CC-Link IE Field delivers high-performance deterministic Ethernet communication optimized for motion control, process automation, and large-scale distributed control applications. Supporting 1 Gbps bandwidth with cycle times down to 31.25 microseconds, this variant enables demanding applications requiring precise synchronization of hundreds of servo axes or real-time coordination of complex production processes.

The protocol supports up to 254 stations per network with massive data capacity (64,512 bytes cyclic data) enabling consolidation of previously separate networks into unified communication infrastructure. Advanced features including time synchronization, quality of service (QoS) prioritization, and redundancy support make IE Field suitable for mission-critical applications requiring maximum reliability and performance.

CC-Link IE TSN (Time-Sensitive Networking)

CC-Link IE TSN represents the latest evolution, incorporating IEEE 802.1 Time-Sensitive Networking standards enabling deterministic communication over standard Ethernet infrastructure while supporting simultaneous IT and OT traffic convergence. This convergence capability eliminates separate networks for control, information, and enterprise connectivity, reducing infrastructure costs while improving data visibility.

TSN extensions including time synchronization (IEEE 802.1AS), traffic scheduling (IEEE 802.1Qbv), and frame preemption (IEEE 802.1Qbu) ensure control traffic determinism regardless of concurrent information traffic volume. This capability enables true Industry 4.0 architectures where shop floor devices communicate directly with cloud services, edge computing platforms, and enterprise systems without compromising real-time control performance.

CC-Link Protocol Comparison

| Feature | CC-Link | CC-Link IE Field Basic | CC-Link IE Field | CC-Link IE TSN | |---------|---------|------------------------|------------------|----------------| | Physical Layer | RS-485 | 100BASE-TX Ethernet | 1000BASE-T Ethernet | 1000BASE-T + TSN | | Max Speed | 10 Mbps | 100 Mbps | 1 Gbps | 1 Gbps | | Min Cycle Time | 0.88 ms | 0.556 ms | 31.25 μs | 31.25 μs | | Max Stations | 64 | 64 | 254 | 254 | | Max Distance | 1,200m @ 156kbps | 100m per segment | 100m per segment | 100m per segment | | Topology | Line/Branch | Star/Ring | Star/Ring | Star/Ring | | QoS Support | No | No | Yes | Yes (TSN) | | IT/OT Convergence | No | Limited | Limited | Full | | Best Application | Legacy systems | Simple Ethernet migration | High-performance motion | Industry 4.0 integration |

Chapter 2: CC-Link Network Architecture

Master-Slave Communication Model

CC-Link protocol implements a master-slave architecture where a single master station controls all network communication, sending output data to slave devices and collecting input data from slaves in coordinated cyclic exchanges. This centralized control ensures deterministic behavior and simplifies network management while preventing communication collisions.

The master station, typically implemented in a PLC or dedicated network controller, maintains a complete map of all connected slave devices, their data allocations, and operational states. The master generates cyclic communication frames at configured intervals, distributing output data to all slaves and collecting response data containing slave inputs and status information.

Cyclic Communication Process

The master initiates each communication cycle by broadcasting a frame containing output data for all slave devices along with synchronization information and sequence counters. Each slave extracts data addressed to its station number, updates outputs accordingly, and prepares response data containing current input states and diagnostic information.

Slaves respond with their data during assigned time slots within the communication cycle, ensuring collision-free data exchange. The master collects all slave responses, updates its input memory areas, and begins preparing the next output frame. This disciplined exchange pattern delivers deterministic performance with predictable timing regardless of network load or device count.

Transient Transmission for Non-Cyclic Data

Beyond cyclic data exchange handling time-critical process data, CC-Link supports transient transmission for non-time-critical configuration, diagnostic, and parameter access. These messages utilize unused bandwidth between cyclic frames, enabling device configuration and monitoring without impacting real-time control performance.

Applications use transient transmission for reading device parameters, modifying configuration settings, retrieving diagnostic information, and accessing manufacturer-specific functionality not included in cyclic data structures. The protocol automatically manages message queuing and retry logic, simplifying application programming.

CC-Link Station Types

Master Station

The master station controls all network activity, initiating cyclic communication and managing transient message transmission. Only one master can be active on a CC-Link network at any time, though redundant master configurations can provide automatic failover in mission-critical applications.

Master stations handle network initialization, station configuration validation, communication error detection, and automatic recovery from transient faults. The master maintains communication statistics, error logs, and operational status for all connected devices accessible through programming interfaces or diagnostic tools.

Local Station

Local stations provide remote I/O functionality, exchanging moderate amounts of cyclic data (up to 256 bytes each direction) with the master station while supporting transient communication for configuration and diagnostics. These stations typically implement I/O blocks, small operator interfaces, or simple device controllers.

Local stations respond to master queries within their assigned time slots, requiring minimal processing capability since the master handles all timing and sequencing logic. This simplicity keeps local station hardware costs low while ensuring reliable operation.

Remote Device Station

Remote device stations connect individual sensors, actuators, and simple field devices to the CC-Link network, exchanging small amounts of cyclic data (typically 1-4 bytes) with minimal overhead. These stations enable economical distribution of simple field devices without requiring local I/O blocks.

The protocol supports up to 64 remote device stations occupying minimal network capacity, making them ideal for distributed sensor networks, discrete actuators, and simple indicators where centralized wiring would be impractical.

Intelligent Device Station

Intelligent device stations implement sophisticated equipment-level processing including servo drives, robots, vision systems, and specialized controllers. These stations exchange large amounts of cyclic data (up to 256 bytes each direction) while supporting extensive transient communication for parameter management and advanced functionality.

Intelligent stations often implement manufacturer-specific profiles defining standardized communication interfaces for specific equipment types. For example, servo drive profiles define standardized positioning commands, status feedback, and diagnostic interfaces ensuring compatibility between PLCs and drives from different manufacturers.

Chapter 3: CC-Link Physical Layer and Wiring

Cable Specifications and Requirements

CC-Link Classic Wiring

Classic CC-Link networks utilize dedicated communication cable with specific electrical characteristics ensuring reliable communication under industrial conditions. The standard specifies twisted-pair cable with overall shield, characteristic impedance between 100-130 Ohms, and conductor size suitable for network length and communication speed requirements.

Recommended Cable Specifications:

• Conductor size: AWG 24 to AWG 20 (0.2 to 0.5 mm²)
• Twisted-pair construction with 100-130 Ohm characteristic impedance
• Overall aluminum/mylar shield with drain wire
• Jacket rated for industrial environments (oil, chemical resistance)
• Minimum bend radius: 10x cable diameter

Popular cable choices include Belden 3106A, Alpha Wire 6412, and equivalent cables from automation suppliers. Using cables meeting or exceeding specifications ensures reliable operation and simplifies troubleshooting by eliminating cable-related issues.

CC-Link IE Ethernet Wiring

CC-Link IE variants utilize standard Ethernet cabling (Cat5e or Cat6) with standard RJ45 connectors, dramatically simplifying installation and reducing material costs compared to proprietary fieldbus cables. Standard Ethernet infrastructure supports CC-Link IE communication without special components.

Ethernet Cable Requirements:

• Category 5e or Category 6 UTP/STP cable
• Standard 100-meter segment length limit
• Standard RJ45 modular connectors
• Shielded cable recommended for industrial environments
• Fiber optic options for long-distance or high-EMI environments

Network Topology and Installation

Line (Daisy-Chain) Topology

Classic CC-Link typically employs line topology where stations connect in series from master through each slave to the last station. This simple topology minimizes cable requirements and simplifies installation, though it provides no redundancy if any cable segment fails.

Line topology requires termination resistors at both network ends (master and final slave) matching the cable characteristic impedance (typically 120-130 Ohms, 1/2W). Proper termination prevents signal reflections that cause communication errors, particularly at higher communication speeds.

Branch Connections

CC-Link supports branch connections where short cable segments (typically limited to 10-20 meters) tap off the main trunk to connect individual stations. Total branch length must be factored into maximum network length calculations to ensure reliable communication.

Excessive branch lengths or too many branches can degrade signal quality, causing communication errors. Best practice limits branches to minimum necessary lengths and considers using T-connectors or junction boxes designed for CC-Link networks.

Ethernet Star and Ring Topologies

CC-Link IE Field and IE TSN support flexible star and ring topologies using standard Ethernet switches. Star topology with managed switches enables sophisticated network management, quality of service (QoS) configuration, and comprehensive diagnostics through standard network management protocols.

Ring topology with redundancy protocols provides automatic failover capability where network communication continues even if a cable segment or switch fails. Redundancy times under 50 milliseconds enable mission-critical applications requiring maximum availability.

Termination and Grounding

Termination Resistors

Proper termination is critical for reliable CC-Link communication, particularly at speeds above 2.5 Mbps where signal reflections cause significant distortion. Termination resistors must be installed at both ends of classic CC-Link networks, matching the cable characteristic impedance.

Termination Requirements:

• Resistance: 120-130 Ohms (match cable impedance)
• Power rating: 1/2 Watt minimum
• Tolerance: 1% for speeds above 5 Mbps
• Location: Installed at master station and final slave only

Many CC-Link devices include built-in termination resistors activated through switches or jumpers. When using built-in termination, ensure only the two end stations have termination enabled while all intermediate stations have termination disabled.

Grounding and Shielding

Proper grounding of CC-Link network shields is essential for noise immunity and reliable communication in electrically hostile industrial environments. Shield grounding should follow single-point grounding principles where the shield connects to earth ground at one location only, typically at the master station.

Grounding Best Practices:

• Ground shield at master station only (single-point grounding)
• Use dedicated cable shield terminal or shield clamp
• Minimize shield ground connection impedance
• Never ground shields at multiple points (creates ground loops)
• Maintain shield continuity through cable runs

Multi-point shield grounding creates ground loops that circulate currents induced by electromagnetic interference, potentially causing communication errors or damage to equipment. If ground potential differences exist between locations, use isolation techniques rather than multi-point grounding.

Chapter 4: CC-Link Communication Model and Data Types

Cyclic Data Exchange

Cyclic data exchange forms the foundation of CC-Link communication, handling time-critical process data with deterministic update rates. The master station sends output data to all slaves and receives input data from all slaves during every communication cycle, ensuring consistent update timing regardless of application program execution or processing variations.

Remote Inputs (RX) and Remote Outputs (RY)

Remote inputs represent data sent from slave stations to the master, typically containing sensor states, device status, and feedback information. Remote outputs represent data sent from master to slaves, typically containing control commands, setpoints, and configuration parameters.

The CC-Link specification allocates remote input and output data in 16-bit words, with allocation sizes depending on station type:

• Remote device stations: 1-4 bits typical
• Local stations: Up to 16 words (256 bytes) each direction
• Intelligent device stations: Up to 16 words (256 bytes) each direction

Link Refresh Time and Communication Performance

Link refresh time represents the interval between successive communication cycles, determining control loop update rates and system responsiveness. CC-Link supports link refresh times from 0.88 milliseconds to several hundred milliseconds depending on communication speed, number of stations, and total data volume.

Application requirements drive link refresh time selection—motion control applications typically require 1-4 millisecond refresh for responsive positioning, while process control applications may operate satisfactorily with 10-50 millisecond refresh rates depending on process dynamics.

Transient Data Transmission

Transient transmission enables non-time-critical data exchange for device configuration, parameter access, diagnostic information, and manufacturer-specific functionality. Unlike cyclic data transmitted every communication cycle, transient messages utilize available bandwidth between cyclic frames, with transmission timing dependent on network load and message priority.

Common Transient Operations:

• Reading and writing device parameters
• Accessing diagnostic information and error logs
• Device identification and capability discovery
• Firmware update and configuration file transfer
• Manufacturer-specific command execution

Application programs typically use transient transmission during initialization sequences, operator-initiated parameter changes, and periodic diagnostic polling rather than time-critical control loops requiring deterministic update rates.

CC-Link Data Types and Registers

CC-Link protocol defines standardized data types ensuring consistent interpretation across different manufacturers' devices:

| Data Type | Size | Range | Typical Use | |-----------|------|-------|-------------| | BIT | 1 bit | 0 or 1 | Digital I/O, status flags | | BYTE | 8 bits | 0-255 | Small integers, codes | | WORD | 16 bits | 0-65,535 or -32,768 to 32,767 | Integer data, setpoints | | DWORD | 32 bits | 0 to 4,294,967,295 | Large values, high-resolution data | | REAL | 32 bits | IEEE 754 floating point | Analog values, engineering units |

Device Buffer Memory

CC-Link devices implement standardized buffer memory structures organizing cyclic data, transient data, status information, and configuration parameters in logical address spaces. Understanding buffer memory organization is essential for proper device integration and programming.

Cyclic input and output data occupy dedicated buffer regions with fixed addresses, enabling fast, deterministic access. Transient and configuration data occupy separate regions accessed through transient communication protocols with variable access times.

Chapter 5: CC-Link Configuration Tutorial with Mitsubishi PLCs

Network Planning and Design

Station Count and Data Allocation

Network design begins with determining required station count and cyclic data volumes. Each station consumes network capacity proportional to its data allocation, with total network capacity limiting maximum station count and refresh time.

CC-Link uses station number allocation from 1-64, with each station assigned a unique number and configured station type. The master reserves station 0, while slaves occupy stations 1-64 based on physical installation order and application requirements.

Communication Speed Selection

Communication speed selection balances performance requirements against physical constraints:

| Speed | Max Distance | Typical Application | Min Cycle Time | |-------|--------------|---------------------|----------------| | 156 kbps | 1,200m | Large facility, slow processes | 14 ms | | 625 kbps | 600m | Typical manufacturing | 5.6 ms | | 2.5 Mbps | 300m | Higher performance | 2.1 ms | | 5 Mbps | 160m | Motion control | 1.4 ms | | 10 Mbps | 100m | High-speed applications | 0.88 ms |

Higher speeds enable faster cycle times but reduce maximum cable lengths, requiring careful layout planning. Many applications balance performance and physical requirements at 2.5 or 5 Mbps communication speeds.

GX Works Configuration for CC-Link

Step 1: CC-Link Master Module Installation

Mitsubishi PLCs implement CC-Link master functionality through dedicated communication modules installed in the PLC base units or expansion racks. Popular modules include QJ61BT11N for Q-Series PLCs and FX3U-64CCL for FX3 series.

Configure the module hardware settings using GX Works configuration dialogs:

1. Launch GX Works 2 or GX Works 3 software
2. Open project and navigate to Module Configuration
3. Add CC-Link master module at appropriate slot position
4. Configure module I/O assignment addresses
5. Set module parameters including communication speed and station allocation

Step 2: Network Parameter Configuration

Configure network parameters defining communication speed, total station count, link refresh mode, and error handling behavior:

Network Configuration Parameters:
- Communication Speed: 2.5 Mbps (example)
- Total Stations: 24 stations
- Link Refresh Mode: Automatic (recommended)
- Link Scan Time: 3.5 ms (calculated)
- Link Special Mode: Enabled for advanced features

Step 3: Slave Station Configuration

Configure each slave station defining station number, station type, and data allocation:

Station 1 Configuration (Remote I/O Block):
- Station Number: 1
- Station Type: Remote I/O (local station)
- Number of Occupied Stations: 2 (determines data size)
- Input Allocation: 32 bytes (2 stations × 16 bytes)
- Output Allocation: 32 bytes (2 stations × 16 bytes)

Station 3 Configuration (Servo Drive):
- Station Number: 3
- Station Type: Intelligent Device Station
- Number of Occupied Stations: 4
- Input Allocation: 64 bytes (4 stations × 16 bytes)
- Output Allocation: 64 bytes (4 stations × 16 bytes)

Step 4: Memory Mapping and Device Allocation

Map CC-Link data to PLC memory areas enabling application program access:

Memory Allocation (Example):
- Remote Inputs (RX): Starting at D1000 (device memory)
  - Station 1 inputs: D1000-D1015 (16 words)
  - Station 3 inputs: D1100-D1131 (32 words)

- Remote Outputs (RY): Starting at D2000
  - Station 1 outputs: D2000-D2015 (16 words)
  - Station 3 outputs: D2100-D2131 (32 words)

- Link Status Registers: Starting at D3000
  - Network status, error codes, diagnostics

Parameter Settings and Testing

Module Parameter Settings

Detailed module parameters control advanced functionality:

RAS (Remote Access Settings):

• Enable/disable remote access for diagnostics
• Configure access passwords and security

Error Handling:

• Communication timeout values
• Error retry counts
• Link scan timeout settings
• Standby master settings (if redundancy used)

Troubleshooting Features:

• Loop-back test mode for hardware verification
• Station-by-station error logging
• Communication statistics counters
• Signal level monitoring

Initial Testing Procedure

Systematic testing validates configuration before full system operation:

1. Hardware verification: Verify all LEDs show expected states (master link OK, slaves ready)
2. Station recognition: Check master recognizes all configured slaves
3. Data exchange test: Manually toggle output bits and verify corresponding slave actions
4. Cycle time verification: Monitor actual link refresh time matches expected values
5. Error injection test: Temporarily disconnect slave and verify proper error detection and recovery

Chapter 6: CC-Link Programming Examples with Mitsubishi FX and Q Series PLCs

Basic Digital I/O Control

Reading Remote Inputs (Ladder Logic)

Ladder Logic - FX3 Series Example:
┃
┃ [D1000.0]──────────────( M100 )  // Station 1, Input Bit 0 to Internal Bit M100
┃
┃ [D1000.1]──────────────( M101 )  // Station 1, Input Bit 1 to Internal Bit M101
┃
┃ [M100]──[M101]─────────( Y0 )    // Logic using CC-Link inputs controls local output
┃

Writing Remote Outputs (Ladder Logic)

Ladder Logic - Writing to Remote Stations:
┃
┃ [X0]────────────────────( M200 )  // Local input to internal bit
┃
┃ [M200]──────────────────( D2000.0 )  // Internal bit to Station 1, Output Bit 0
┃
┃ [M201]──[M202]──────────( D2000.5 )  // Logic result to remote output bit
┃

Analog Data Exchange

Reading Analog Input from Remote Station

Structured Text - Q Series Example:
// Read 16-bit analog value from Station 3, Word 0
AnaloginputRaw := D1100;  // Raw ADC value (0-4095 for 12-bit)

// Convert to engineering units (0-10V represented as 0-4095)
AnalogVoltage := INT_TO_REAL(AnalogInputRaw) * 10.0 / 4095.0;

// Apply scaling for process variable (e.g., 0-10V = 0-100°C)
Temperature := AnalogVoltage * 10.0;  // 1V per 10°C

Writing Analog Output to Remote Station

Structured Text - Analog Output:
// Calculate analog output value
SetpointVoltage := ProcessSetpoint / 10.0;  // Convert °C to voltage

// Convert to 12-bit DAC value
DACValue := REAL_TO_INT(SetpointVoltage * 4095.0 / 10.0);

// Limit to valid range
IF DACValue < 0 THEN
    DACValue := 0;
ELSIF DACValue > 4095 THEN
    DACValue := 4095;
END_IF;

// Write to station 3, analog output word
D2100 := DACValue;

Servo Drive Control via CC-Link

Position Control Example

Structured Text - Servo Positioning:
// Station 5 is servo drive (intelligent device station)
// Control word at D2200, position command at D2202-D2203 (32-bit)

// Enable servo drive
D2200.0 := TRUE;  // Servo ON command
D2200.1 := FALSE;  // Reset alarm
D2200.8 := TRUE;  // Position control mode

// Send position command (in encoder pulses)
D2202 := DWORD_TO_WORD(TargetPosition);  // Lower 16 bits
D2203 := DWORD_TO_WORD(SHR(TargetPosition, 16));  // Upper 16 bits

// Read servo status
ServoReady := D1200.0;  // Servo ready bit
ServoInPosition := D1200.1;  // In-position flag
ServoAlarm := D1200.7;  // Alarm status

// Read actual position
ActualPosition := WORD_TO_DWORD(D1202) OR SHL(WORD_TO_DWORD(D1203), 16);

Error Handling and Diagnostics

CC-Link Communication Status Monitoring

Structured Text - Status Monitoring:
// Link status registers typically start at D3000 (verify in module settings)
LinkStatus := D3000.0;  // Overall link status (1=normal, 0=error)
LinkScanning := D3000.1;  // Link scan in progress

// Station participation status
Station1Online := D3001.0;  // Station 1 participating
Station2Online := D3001.1;  // Station 2 participating
Station3Online := D3001.2;  // Station 3 participating

// Error detection and logging
IF NOT LinkStatus THEN
    ErrorCode := D3010;  // Read error code register
    ErrorStation := D3011;  // Station number with error

    // Log error to HMI or SCADA
    CASE ErrorCode OF
        16#10: ErrorMessage := 'Communication timeout';
        16#20: ErrorMessage := 'Parameter mismatch';
        16#30: ErrorMessage := 'Station not responding';
        ELSE
            ErrorMessage := 'Unknown error';
    END_CASE;
END_IF;

Chapter 7: CC-Link IE Field - Ethernet-Based CC-Link

CC-Link IE Field Architecture

CC-Link IE Field delivers high-performance deterministic Ethernet communication supporting 1 Gbps bandwidth with cycle times down to 31.25 microseconds. This performance enables demanding motion control applications coordinating hundreds of servo axes or large distributed control systems consolidating previously separate networks.

Performance Advantages

IE Field networks support up to 254 stations with 64,512 bytes of cyclic data capacity per network, dramatically exceeding classic CC-Link limitations. This expanded capacity enables consolidation of control architectures, reducing hardware costs and simplifying system integration while improving overall performance.

Sub-100 microsecond cycle times enable precision motion control applications requiring exact coordination between multiple axes including electronic gearing, camming, and synchronized material handling. Jitter performance under 1 microsecond ensures consistent control loop execution critical for quality in high-speed manufacturing processes.

IE Field Network Construction

Managed Switch Requirements

CC-Link IE Field networks require managed Ethernet switches supporting VLAN (Virtual LAN) configuration, Quality of Service (QoS) prioritization, and IGMP (Internet Group Management Protocol) snooping. These features ensure CC-Link protocol frames receive priority over other traffic and multicast efficiency prevents bandwidth waste.

Recommended Switch Features:

• IEEE 802.1Q VLAN support for network segmentation
• IEEE 802.1p/DSCP QoS for traffic prioritization
• IGMP snooping for efficient multicast handling
• Port mirroring for diagnostics and troubleshooting
• Ring redundancy protocols (if redundancy required)
• Sufficient backplane bandwidth preventing bottlenecks

Popular switch choices include Mitsubishi RH series industrial switches specifically designed for IE Field, though many third-party industrial switches meeting specifications work reliably.

Network Design Considerations

Proper IE Field network design considers switch placement, backbone links, redundancy requirements, and integration with other networks:

Single Network Design:

• Master connected to core switch
• Slave devices distributed across access switches
• Gigabit uplinks between switches
• Ring topology with redundancy protocol for critical applications

Multiple Network Integration:

• Separate VLANs for different IE Field networks
• Layer 3 routing for inter-network communication
• Firewall integration for security segmentation
• Connection to plant-level information networks

Configuration and Programming Differences

IE Field configuration follows similar principles to classic CC-Link but utilizes GX Works 3 software with IE Field module support. Configuration includes network topology definition, QoS settings, and VLAN assignments in addition to standard station configuration.

IE Field Module Configuration

Network Configuration (IE Field):
- Network Type: CC-Link IE Field
- Communication Speed: 1 Gbps
- Cycle Time: 0.5 ms (example for motion control)
- Total Stations: 45
- VLAN ID: 100 (dedicated VLAN for CC-Link)
- QoS Priority: 6 (high priority for real-time traffic)

Programming Model

IE Field uses identical programming models as classic CC-Link—application programs access remote I/O through device memory addresses without protocol-specific programming. This compatibility simplifies migration from classic CC-Link to IE Field, often requiring only configuration changes without application program modifications.

Chapter 8: CC-Link IE TSN - Time-Sensitive Networking

TSN Technology Integration

CC-Link IE TSN incorporates IEEE 802.1 Time-Sensitive Networking standards enabling deterministic communication over standard Ethernet infrastructure while simultaneously supporting non-deterministic IT traffic. This convergence eliminates separate physical networks for control, information, and enterprise connectivity, reducing costs and improving data accessibility.

Key TSN Standards in CC-Link IE TSN:

IEEE 802.1AS (Time Synchronization) Provides precise time synchronization across all network devices with sub-microsecond accuracy, ensuring coordinated operation of distributed control systems. All devices maintain synchronized time base enabling exact correlation of events, coordinated control sequences, and synchronized data logging.

IEEE 802.1Qbv (Time-Aware Shaper) Implements time-based traffic scheduling where critical control traffic transmits during protected time windows while other traffic transmits during remaining time periods. This scheduling guarantees control traffic delivery within bounded latency regardless of information traffic volume.

IEEE 802.1Qbu (Frame Preemption) Enables interruption of low-priority frame transmission to immediately transmit higher-priority control frames, minimizing latency jitter and ensuring consistent cycle timing even under heavy network load.

IEEE 802.1CB (Frame Replication and Elimination) Provides seamless redundancy where critical frames transmit over multiple paths with automatic duplicate elimination at receivers. This mechanism delivers sub-millisecond failover times while maintaining zero packet loss during network failures.

IT/OT Convergence Capabilities

CC-Link IE TSN enables true convergence of operational technology (OT) control networks with information technology (IT) data networks, allowing industrial devices to communicate directly with enterprise systems, cloud platforms, and edge computing resources without separate network infrastructure.

Convergence Benefits:

Reduced Infrastructure Costs: Eliminating duplicate network installations for control and information systems significantly reduces cabling, switches, and maintenance costs while simplifying facility design and installation.

Improved Data Visibility: Direct connectivity between shop floor devices and enterprise systems enables real-time data access for analytics, optimization, and decision support without intermediate data collection systems or protocol gateways.

Simplified Architecture: Unified network architecture reduces complexity, simplifies troubleshooting, and improves maintainability compared to traditional separate network approaches requiring complex integration gateways.

Enhanced Security: TSN-enabled networks support sophisticated segmentation and access control through VLANs, access control lists, and microsegmentation providing defense-in-depth security appropriate for converged environments.

TSN Network Design

TSN-Capable Switch Selection

CC-Link IE TSN networks require switches supporting complete TSN feature sets including time synchronization, scheduled traffic, and frame preemption. As TSN technology matures, more industrial switch vendors offer compliant products though currently options remain more limited than standard managed switches.

Configuration Complexity

TSN network configuration requires careful planning of traffic schedules, bandwidth allocation, and redundancy paths. CLPA provides configuration tools and reference designs simplifying TSN deployment, though expertise requirements exceed classic CC-Link or basic IE Field implementations.

Professional services from CLPA members or automation system integrators with TSN expertise should be considered for initial TSN deployments until engineering teams develop internal capabilities.

Chapter 9: CC-Link Diagnostics and Troubleshooting

Diagnostic Tools and Methods

LED Indicators

CC-Link modules and devices provide LED indicators showing operational status:

Master Module LEDs:

• RUN (Green): Normal operation, link scanning active
• ERR (Red): Communication error detected
• L RUN (Green): Link operational, all stations communicating
• L ERR (Red): Link error, one or more stations not responding

Slave Device LEDs:

• PWR (Green): Power supply normal
• RUN (Green): Device operating normally
• COM (Green): Communication active with master
• ERR (Red): Device error or communication failure

Software Diagnostics

GX Works provides comprehensive diagnostic capabilities:

Network Monitor:

• Real-time station status display
• Cyclic data monitoring
• Communication error counters
• Link scan timing analysis
• Signal quality indicators

Error Log:

• Timestamped error events
• Error codes with descriptions
• Affected station identification
• Error frequency statistics

Oscilloscope and Bus Analyzer

Hardware diagnostic tools enable physical layer analysis:

Uses for Oscilloscope:

• Signal voltage level verification
• Rise/fall time measurement
• Noise and interference identification
• Termination verification through reflection analysis

Uses for Bus Analyzer:

• Message-level protocol analysis
• Timing verification
• Intermittent error capture
• Transient message monitoring

Common CC-Link Issues and Solutions

Problem: Link Will Not Start (All Stations Offline)

Symptoms: Master module ERR LED on, no stations participating in communication, link scan does not begin.

Causes:

• Incorrect communication speed configuration between master and slaves
• Missing or incorrect termination resistors
• Cable wiring errors (reversed polarity, opens)
• Power supply problems at master or slaves

Solutions:

1. Verify communication speed settings match on master and ALL slaves
2. Measure termination resistance at network ends (should be ~60-65 Ohms)
3. Check cable continuity and polarity using multimeter
4. Verify power supply voltages at all devices (24VDC ±10%)
5. Try reducing communication speed to 156 kbps for initial testing

Problem: Intermittent Communication Errors

Symptoms: Stations randomly drop offline and reconnect, periodic error LED indications, communication timeout errors in logs.

Causes:

• Electrical noise from nearby motors, drives, or switching power supplies
• Marginal cable quality or connections
• Excessive cable length for selected communication speed
• Ground loops or improper shielding

Solutions:

1. Route CC-Link cable away from power cables (minimum 4-inch separation)
2. Use shielded cable with proper shield grounding
3. Check all connector terminations for proper crimping/screw terminals
4. Verify total cable length within specifications for communication speed
5. Add ferrite chokes if EMI suspected
6. Verify single-point shield grounding (no ground loops)

Problem: Specific Station Not Communicating

Symptoms: One station never comes online while others work properly, station-specific error indications.

Causes:

• Incorrect station number setting on device
• Station configuration mismatch between master and slave
• Cable problem at specific station drop
• Device hardware failure
• Incompatible device firmware version

Solutions:

1. Verify station number rotary switch/DIP switch setting matches master configuration
2. Check station type and occupied station count match between master config and device
3. Test cable at problem station location for continuity and termination
4. Swap suspected device with known-good device to isolate hardware problems
5. Update device firmware to version recommended by master module documentation

Problem: Slow Cycle Times / Performance Issues

Symptoms: Actual link scan time longer than expected, sluggish system response, delayed output reactions.

Causes:

• Total configured data exceeds network capacity
• Communication speed too low for application
• Excessive transient transmission loading
• Network configuration errors

Solutions:

1. Calculate actual link scan time based on station count, data allocations, and speed
2. Reduce data allocations by removing unused remote I/O points
3. Increase communication speed if cable length permits
4. Minimize transient message frequency during time-critical operations
5. Review station configuration ensuring no duplicate station allocations

Preventive Maintenance

Regular Inspection Schedule:

Monthly:

• Visual inspection of cable routing and connections
• LED status verification on all modules
• Review error logs for patterns or warnings

Quarterly:

• Cable connection tightness verification
• Shield ground integrity testing
• Communication statistics analysis
• Performance timing verification

Annually:

• Complete network documentation review
• Backup of all configuration files
• Spare parts inventory verification
• Training refresh for maintenance personnel

Chapter 10: CC-Link vs Other Industrial Protocols

CC-Link vs PROFINET

Market Focus:

• CC-Link: Dominant in Asian markets (Japan, China, South Korea)
• PROFINET: Dominant in European markets, strong Siemens ecosystem

Performance:

• CC-Link IE Field: 31.25 μs minimum cycle time, 1 Gbps
• PROFINET IRT: 31.25 μs minimum cycle time, 100 Mbps typical

Openness:

• Both protocols are open standards with extensive vendor support
• CC-Link: CLPA manages specifications, no licensing fees
• PROFINET: PI (PROFIBUS & PROFINET International) manages, conformance testing required

Best Choice:

• CC-Link: Asian market deployments, Mitsubishi PLC ecosystems
• PROFINET: European deployments, Siemens PLC ecosystems

CC-Link vs EtherNet/IP

Protocol Philosophy:

• CC-Link: Purpose-built industrial protocol with dedicated features
• EtherNet/IP: Industrial adaptation of standard TCP/IP and CIP

Performance:

• CC-Link IE Field: Higher determinism through dedicated design
• EtherNet/IP: Excellent performance with modern implementations

Market Position:

• CC-Link: Leading in Asian markets
• EtherNet/IP: Leading in North American markets, strong Rockwell Automation ecosystem

Integration:

• CC-Link: Best integration with Mitsubishi, Omron Asian market products
• EtherNet/IP: Best integration with Allen-Bradley, widespread device support

Detailed protocol comparisons available in our comprehensive PLC Communication Protocols Guide.

Chapter 11: CC-Link Best Practices

Network Design Best Practices

Plan for Future Expansion Design networks with 20-30% capacity margin enabling future device additions without network redesign. Reserve unused station numbers in logical groupings simplifying future integration.

Document Thoroughly Maintain complete network documentation including:

• Network topology diagrams with cable lengths
• Station number assignments and device types
• Configuration parameter backups
• Wiring diagrams and termination locations
• IP address assignments (IE Field/TSN)
• Switch configurations and VLAN assignments

Implement Consistent Naming Use systematic naming conventions for stations, data registers, and configuration parameters. Consistent naming simplifies programming, troubleshooting, and maintenance.

Example Naming Convention:

Station Names: ZONE_FUNCTION_NUMBER
- ASSEMBLY_IO_01 (Assembly area I/O block 1)
- ASSEMBLY_SERVO_03 (Assembly area servo drive 3)
- PAINT_ROBOT_01 (Paint booth robot 1)

Data Registers:
- D1xxx: Remote inputs from assembly area
- D2xxx: Remote outputs to assembly area
- D3xxx: Assembly area status and diagnostics

Configuration Best Practices

Use Latest Firmware Maintain devices at current firmware versions ensuring bug fixes, performance improvements, and security updates. Establish firmware update procedures including:

• Testing updates in development environment before production deployment
• Maintaining firmware version documentation
• Coordinating updates during planned maintenance windows
• Keeping backup configurations before updates

Minimize Cyclic Data Allocate only necessary data to cyclic transmission, reducing network load and enabling faster cycle times. Use transient transmission for infrequently accessed parameters, diagnostics, and configuration data.

Optimize Station Allocation Position high-bandwidth stations (servo drives, vision systems) early in station number sequence minimizing latency to time-critical devices.

Programming Best Practices

Implement Structured Error Handling

Structured Text - Comprehensive Error Handling:
// Monitor CC-Link status systematically
IF CC_Link_Status.LinkOK THEN
    // Normal operation
    ProcessControl();
ELSE
    // Link error detected
    SafeShutdown();

    IF CC_Link_Status.ErrorCode = TIMEOUT_ERROR THEN
        // Specific error handling
        AttemptRecovery();
        IncrementTimeoutCounter();

        IF TimeoutCounter > MAX_RETRIES THEN
            RaiseAlarm('CC-Link communication failed');
        END_IF;
    END_IF;
END_IF;

Use Heartbeat Monitoring

Implement application-level heartbeat mechanisms detecting communication failures faster than protocol timeouts:

// Increment heartbeat counter each cycle
Station_3_Heartbeat := D1100.0;  // Read heartbeat bit from station 3

IF Station_3_Heartbeat <> Last_Heartbeat THEN
    Last_Heartbeat := Station_3_Heartbeat;
    Heartbeat_Timeout_Counter := 0;
ELSE
    Heartbeat_Timeout_Counter := Heartbeat_Timeout_Counter + 1;

    IF Heartbeat_Timeout_Counter > 50 THEN  // ~50 cycles without change
        // Device likely frozen or offline
        RaiseDeviceAlarm(3);
    END_IF;
END_IF;

Chapter 12: Frequently Asked Questions About CC-Link Protocol

What is CC-Link protocol used for?

CC-Link protocol is used for industrial automation communication connecting PLCs to remote I/O, sensors, actuators, servo drives, robots, and other control devices. The protocol supports applications including manufacturing automation, motion control, process automation, and building automation, with particular strength in Asian markets where CC-Link represents the dominant industrial networking standard.

What is the difference between CC-Link and CC-Link IE Field?

CC-Link uses dedicated RS-485 serial communication at speeds up to 10 Mbps supporting 64 stations, while CC-Link IE Field uses Gigabit Ethernet supporting 254 stations with cycle times down to 31.25 microseconds. IE Field provides dramatically higher performance and capacity suitable for demanding motion control and large distributed control applications, while classic CC-Link serves applications where proven fieldbus technology meets requirements.

What does CC-Link IE stand for?

CC-Link IE stands for "CC-Link Industrial Ethernet," representing the Ethernet-based variants of CC-Link protocol family including CC-Link IE Field Basic, CC-Link IE Field, and CC-Link IE TSN. These Ethernet variants provide higher performance and capacity than classic CC-Link while maintaining protocol compatibility and familiar programming models.

How do I configure CC-Link on Mitsubishi PLC?

Configure CC-Link on Mitsubishi PLCs using GX Works 2 or GX Works 3 software: Install the CC-Link master module in the PLC, configure module parameters including communication speed and station allocation, define each slave station with station number and data allocation, map CC-Link data to PLC device memory, and download configuration to the PLC. Detailed configuration steps vary by PLC series (FX, Q, L, iQ-F, iQ-R) but follow similar principles.

What is CC-Link TSN?

CC-Link TSN (Time-Sensitive Networking) is the latest CC-Link variant incorporating IEEE 802.1 TSN standards enabling deterministic real-time control communication while simultaneously supporting IT traffic on the same physical network. TSN technology enables true IT/OT convergence where industrial devices communicate directly with enterprise systems, cloud services, and edge computing platforms without separate network infrastructure.

What cable is used for CC-Link?

Classic CC-Link uses dedicated twisted-pair cable with overall shield, 100-130 Ohm characteristic impedance, and AWG 20-24 conductors. Popular cables include Belden 3106A and Alpha Wire 6412. CC-Link IE variants use standard Ethernet cable (Cat5e or Cat6) with standard RJ45 connectors, simplifying installation and reducing costs.

How many devices can connect to CC-Link network?

Classic CC-Link supports up to 64 stations with maximum station allocations depending on device types and data volumes. CC-Link IE Field Basic supports 64 stations, while CC-Link IE Field and CC-Link IE TSN support up to 254 stations per network with significantly higher data capacity enabling larger distributed control systems.

What is the maximum distance for CC-Link communication?

Classic CC-Link maximum distance varies by communication speed: 1,200 meters at 156 kbps, 600 meters at 625 kbps, 300 meters at 2.5 Mbps, 160 meters at 5 Mbps, and 100 meters at 10 Mbps. CC-Link IE variants follow standard Ethernet distance limits of 100 meters per cable segment, extendable using switches or fiber optic converters for longer distances.

Is CC-Link compatible with other protocols?

CC-Link networks can interface with other industrial protocols including PROFINET, EtherNet/IP, Modbus TCP, and PROFIBUS through protocol gateway devices or multi-protocol PLCs supporting multiple communication modules. Mitsubishi PLCs support simultaneous operation of CC-Link with other protocols enabling integration of multi-vendor equipment.

What PLCs support CC-Link protocol?

Mitsubishi PLCs including FX, Q, L, iQ-F, and iQ-R series provide native CC-Link support through integrated ports or add-on communication modules. Many other PLC manufacturers including Omron, Panasonic, Keyence, and Fuji Electric offer CC-Link support through dedicated communication modules, enabling CC-Link integration across diverse automation ecosystems.

How do I troubleshoot CC-Link communication errors?

Troubleshoot CC-Link errors using systematic approach: Check LED indicators on master and slave devices, review error logs in GX Works diagnostics, verify communication speed settings match between all devices, test cable continuity and termination resistance, measure signal levels with oscilloscope if available, and isolate problem devices by testing stations individually. Most issues relate to configuration mismatches, wiring errors, or electrical noise.

What is the CC-Link Partner Association (CLPA)?

The CC-Link Partner Association (CLPA) is the international organization maintaining CC-Link specifications, certifying compliant devices, providing technical training, and promoting CC-Link adoption worldwide. CLPA has over 3,000 member companies and regional offices in Japan, China, Europe, and Americas supporting global CC-Link deployment.

Conclusion: Master CC-Link Protocol for Industrial Automation Success in Asian Markets

CC-Link protocol mastery has become essential for automation engineers working in Asian markets or integrating Asian-manufactured equipment into global automation systems. The protocol family's comprehensive coverage from simple fieldbus applications through cutting-edge TSN-based Industry 4.0 architectures ensures CC-Link remains relevant as industrial automation evolves toward higher performance, greater connectivity, and seamless IT/OT convergence.

Understanding the distinct characteristics and appropriate applications for each CC-Link variant—classic CC-Link for proven fieldbus reliability, CC-Link IE Field Basic for cost-effective Ethernet migration, CC-Link IE Field for high-performance motion control, and CC-Link IE TSN for Industry 4.0 convergence—enables optimal protocol selection matching application requirements while maintaining future-proof architecture supporting long-term system evolution.

The extensive vendor support through CLPA's 3,000+ member companies ensures broad device availability, competitive pricing, and continued innovation maintaining CC-Link competitiveness with European and North American protocol alternatives. For organizations with global operations, understanding both CC-Link and competing protocols enables optimal equipment selection and seamless integration across diverse geographic markets.

Related Industrial Automation Resources

Expand your industrial communication protocol knowledge with complementary resources:

• PLC Communication Protocols Complete Guide - Comprehensive overview of Modbus, EtherNet/IP, PROFINET, and other protocols
• EtherCAT Protocol Tutorial - Master high-performance Beckhoff EtherCAT communication
• PROFINET vs EtherNet/IP Comparison - Compare leading industrial Ethernet protocols
• Modbus RTU Protocol Tutorial - Learn universal Modbus serial communication
• Siemens PLC Programming Tutorial - Master Siemens PLC programming with PROFINET integration

Accelerate Your Industrial Networking and PLC Programming Career

Ready to become an industrial automation expert with comprehensive protocol knowledge spanning global standards? Our complete PLC Programming Master Guide covers everything from fundamental PLC concepts to advanced industrial communication techniques including CC-Link, EtherCAT, PROFINET, and EtherNet/IP. Access comprehensive resources, practical examples, and expert guidance to master the skills driving modern industrial automation across global markets.

Continue developing your CC-Link expertise through hands-on implementation projects, formal training from CLPA-certified providers, and staying current with emerging CC-Link TSN developments and device profiles expanding protocol capabilities and application range throughout 2025 and beyond.