CC-Link is an open industrial fieldbus designed for fast and deterministic communication between PLCs, remote I/O, motor drives, sensors and other automation equipment. Classic CC-Link uses an EIA RS-485-compatible physical layer and supports both cyclic I/O exchange and transient message communication.

In simple terms: a PLC can use CC-Link to collect input information from industrial sensors, exchange I/O data with remote modules and send commands or references to a variable frequency drive over one industrial network.

Where did CC-Link come from?

CC-Link was originally developed by Mitsubishi Electric in 1996. Mitsubishi Electric released the CC-Link specifications for open use in June 2000, and the CC-Link Partner Association — CLPA — was established later that year to promote interoperability and multi-vendor development.

Its Mitsubishi origin does not mean CC-Link is limited to Mitsubishi products. The CLPA ecosystem includes devices from many manufacturers, including controllers, I/O systems, drives, valves, instruments and communication modules.

How does classic CC-Link work?

Classic CC-Link uses a broadcast polling communication system. A manager station controls the network cycle, while device stations exchange their assigned cyclic I/O and register data with the manager.

This makes CC-Link suitable for regular machine I/O. For example, a proximity sensor can connect to a remote input module, while a digital output on the same network controls a contactor, solenoid valve or other machine actuator.

Network information can be presented to operators on an HMI panel, while production data, alarms and status information collected by the PLC can be forwarded to a SCADA system.

What are RX, RY, RWr and RWw in CC-Link?

Classic CC-Link provides defined cyclic link areas for bit and word data:

RX: Remote input bits transferred from a device station to the manager.
RY: Remote output bits transferred from the manager to a device station.
RWr: Remote register words transferred from a device station to the manager.
RWw: Remote register words transferred from the manager to a device station.

For example, an analog input module can place a process measurement in RWr, while the PLC sends a reference or setpoint through RWw to a controller or compatible drive.

Which communication speeds does CC-Link support?

Classic CC-Link supports five standard communication rates:

156 kbit/s
625 kbit/s
2.5 Mbit/s
5 Mbit/s
10 Mbit/s

As communication speed increases, the maximum cable distance decreases. With CC-Link Version 1.10 compatible cable, typical maximum total cable lengths are approximately:

156 kbit/s: 1200 m
625 kbit/s: 900 m
2.5 Mbit/s: 400 m
5 Mbit/s: 160 m
10 Mbit/s: normally 80 m, or up to 100 m when the additional specified cabling conditions are satisfied.

CC-Link therefore cannot be described as a network that always provides 1200 m transmission distance. The required cycle time and physical machine size need to be considered together.

How many devices can be connected to classic CC-Link?

Classic CC-Link supports up to 64 device stations. Actual network capacity also depends on how many stations each device occupies and how much cyclic data is assigned to it.

A simple remote digital I/O block may require only a small amount of link data, while a sophisticated drive or intelligent control device can require more remote register capacity.

Which cable does classic CC-Link use?

Classic CC-Link uses a dedicated shielded three-core twisted-pair CC-Link cable and an EIA RS-485-compatible bus physical layer.

Unlike DeviceNet, the classic CC-Link data cable is not normally used as the general 24 VDC field-device power bus. Remote I/O, sensors and communication adapters that need separate DC power should be supplied from an appropriate industrial power supply.

Cable routing is also important. CC-Link communication cable should not run for long distances directly beside high-current wiring for contactors, circuit breakers and switchgear.

Where a cabinet contains powerful VFDs or servo drives, correct shielding, grounding and cable separation help reduce electromagnetic interference on the network.

How is classic CC-Link terminated?

A bus-type CC-Link network requires termination at the two physical ends of the communication trunk. CC-Link Version 1.10 compatible installations use 110 Ω terminating resistors.

A terminating resistor should not be fitted to every station. Intermediate devices remain connected along the bus, while termination is applied only at the two physical ends.

How are sensors used with CC-Link?

A conventional inductive, capacitive or photoelectric sensor does not need to contain a CC-Link interface. Its NPN, PNP or analog output can connect to a CC-Link remote I/O module, which then transfers the sensor state or measured value to the PLC.

More intelligent instruments can also include a native CC-Link communication interface. Process measurements such as pressure, temperature or position can then be transferred as word data instead of conventional individual I/O signals.

Can an encoder connect to CC-Link?

A conventional A/B/Z incremental encoder is not normally a native CC-Link station. Its pulse signals are generally read by a high-speed counter, PLC module or motion controller.

The controller can then exchange calculated speed, position or machine-state information through CC-Link. An encoder using RS-422 differential outputs such as A/A− and B/B− should therefore not be confused with a CC-Link network device.

Can CC-Link be used with servo systems?

Compatible servo drives and motors can use CC-Link for status data, commands, alarms and parameter exchange with the PLC.

Classic CC-Link, however, should not automatically be treated as a precision multi-axis motion-synchronization bus. Applications requiring tightly synchronized positioning may use a dedicated motion network or newer Ethernet-based technologies within the broader motion control architecture.

Where is CC-Link used in machines and production lines?

CC-Link has been widely used in assembly, automotive, packaging, material-handling, semiconductor and general factory-automation systems.

One production cell can combine remote I/O, proximity sensors, a conveyor VFD, valve manifolds, controllers and servo equipment. CC-Link allows those field devices to exchange process data with the main PLC without requiring a separate dedicated communication cable for every intelligent device.

The PLC and network data can also feed higher-level operator interfaces and plant-monitoring systems instead of remaining isolated at machine level.

Is classic CC-Link Ethernet?

No. Classic CC-Link is an RS-485-compatible serial fieldbus, not standard Ethernet. A classic CC-Link cable cannot simply be connected to an Ethernet switch.

General Ethernet and the Ethernet-based members of the CC-Link family should therefore be treated as separate technologies.

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

Classic CC-Link is an RS-485-compatible fieldbus operating at up to 10 Mbit/s. CC-Link IE refers to later Ethernet-based members of the CC-Link family.

The family includes technologies such as CC-Link IE Controller Network, CC-Link IE Field Network, CC-Link IE Field Basic and CC-Link IE TSN. These are not simply classic CC-Link with a different connector.

What is CC-Link IE TSN?

CC-Link IE TSN combines industrial Ethernet with Time-Sensitive Networking concepts. Current CLPA implementations support 1 Gbit/s and 100 Mbit/s physical layers.

Time synchronization and scheduled traffic mechanisms allow control, motion and information traffic to coexist on an Ethernet-based architecture.

An important distinction is that TSN is not a feature of classic CC-Link. It belongs to the newer CC-Link IE TSN generation.

What is the difference between CC-Link and Modbus?

Modbus is a general-purpose application protocol based around function codes and data objects such as registers and coils. Modbus RTU commonly operates on RS-485, while Modbus TCP operates over Ethernet and TCP/IP.

Classic CC-Link is a complete fieldbus system with its own cyclic I/O mapping, station model, framing and network timing.

Neither technology is universally better. Modbus can be convenient where simple register-based interoperability is required, while CC-Link can be a natural fit in a machine already built around Mitsubishi PLCs, remote I/O and compatible automation equipment.

What is the difference between CC-Link and CANopen?

CANopen is a different industrial communication system built on CAN technology. Classic CC-Link instead uses its own RS-485-compatible fieldbus layer.

The two systems have different addressing, configuration and messaging structures. A CANopen device and a CC-Link device cannot communicate by using a simple wiring adapter; a protocol gateway is required.

What is the relationship between CC-Link and Mitsubishi?

Because CC-Link was originally developed by Mitsubishi Electric, it has historically been strongly represented in Mitsubishi factory-automation systems.

A Mitsubishi-based production machine may contain a PLC, Mitsubishi GOT HMI, VFDs, remote I/O and third-party CC-Link devices on the same automation platform.

The technology's later development as an open network means compatible products are not limited to one manufacturer.

Is there a universal CC-Link C programming API?

No. There is no universal CC-Link standard API named `cclink_init()`, `cclink_write_word()` or `cclink_close()` that can be assumed to exist on every platform.

The programming method depends on the actual PLC, master module, PC interface card, embedded communication module or vendor SDK.

In many PLC systems, CC-Link parameters are configured through the engineering software, RX/RY and RWr/RWw areas are mapped into PLC memory, and the ladder or Structured Text program simply reads and writes those mapped data areas.

Why does a CC-Link network fail to communicate?

Start with the physical layer. Check the correct CC-Link cable, shield connection, station-to-station wiring and the 110 Ω termination at the two physical ends of the bus.

Inside a cabinet containing switch-mode power supplies, contactors, VFDs and servo amplifiers, cable routing and grounding become especially important because high-frequency electrical noise can affect communication quality.

Next check communication speed, station numbers and occupied-station settings. All devices on one classic CC-Link network must use compatible network parameters.

If the station appears online but machine data is wrong, inspect RX/RY and RWr/RWw mapping inside the PLC. A control device being visible on the network does not guarantee that the PLC program is reading the correct link area.

If a machine input appears incorrect, also check the physical sensor, its 24 V supply and the remote-I/O input LED. A fault that appears to be a network problem may actually be a field-wiring or power-supply fault.

Practical CC-Link troubleshooting checklist

1. Are all stations configured for the same communication speed?

2. Are station numbers and occupied-station settings correct?

3. Is approved CC-Link cable being used?

4. Are suitable 110 Ω terminating resistors installed at both physical ends?

5. Is the total cable length within the limit for the selected communication speed?

6. Is the communication cable routed correctly away from high-power wiring?

7. Are RX/RY and RWr/RWw areas mapped to the correct PLC addresses?

8. Are the field device, sensor and 24 VDC power supply actually healthy?

Related Industrial Communication Guides

Industrial Communication · Ethernet · Modbus · CANopen

Related Field and Automation Pages

PLCs · HMI Panels · SCADA · Sensors · Encoders · Servo Systems · Motion Control · AC Drives and VFDs · Power Supplies · Switchgear · Controllers