# IO-Link

Protocols · `IO-Link` · verification: source checked

IO-Link is a standardized point-to-point communication technology for sensors and actuators, specified in IEC 61131-9. It uses a three-wire sensor and actuator connection and can be integrated into fieldbuses. It supports bidirectional communication for diagnostics and parameterization at three communication speeds: 4.8 kBaud, 38.4 kBaud, and 230.4 kBaud.

## Specification

| Property | Value |
|---|---|
| Transports | serial |
| Architecture | master slave |
| Encoding | binary |
| Standard body | IEC |
| Standard ref | IEC 61131-9 |

## Connected

- Related: [EtherCAT](https://machineschema.com/protocol/ethercat.md)
- Supported by: [Hermle C 42 GEN2](https://machineschema.com/hardware/hermle-c-42-gen2.md), [KEYENCE CS-LC125PC](https://machineschema.com/hardware/keyence-cs-lc125pc.md), [KEYENCE CS-LC60PC](https://machineschema.com/hardware/keyence-cs-lc60pc.md), [KEYENCE CS-LGS30PC](https://machineschema.com/hardware/keyence-cs-lgs30pc.md)

## Safety

- IO-Link Safety supports functional safety applications.
- IO-Link Safety Masters implement communication in higher-level systems such as PROFIsafe, CIPsafety or FSOE (Safety over EtherCAT).
- IO-Link Safety Devices can be used unchanged in higher-level systems.

## Study notes

- IO-Link is not a fieldbus; it is a point-to-point connection technology for sensors and actuators.
- IO-Link uses standard M12, M8 or M5 connectors and three-wire cables.
- IO-Link supports three communication speeds: 4.8 kBaud, 38.4 kBaud and 230.4 kBaud.
- IODD (IO Device Description) is delivered as a compressed ZIP file containing the main IODD file, optional language and image files, and the manufacturer's declaration.
- IO-Link device profiles standardize process data, parameters and functions for sensors.
- IO-Link Wireless removes physical cables while maintaining real-time communication between sensors, actuators and control systems.

## Sources

1. [IO-Link Technology: Smarter, More Efficient Communication](https://io-link.com/technology) (accessed 2026-10-25)
2. [IEC 61131:2026 SER](https://webstore.iec.ch/en/publication/62427) (accessed 2026-10-25)

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