# IO-Link Safety

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

IO-Link Safety is a functional safety communication protocol that uses IO-Link as a black channel for safety-related data. It is standardized as IEC 61139-2 and supports applications up to SIL 3 over point-to-point IO-Link connections. IO-Link Safety Masters integrate the safety communication into higher-level systems, and mix mode allows safety-related and standard data to be transmitted at the same time.

## Specification

| Property | Value |
|---|---|
| Transports | other |
| Architecture | master slave |
| Encoding | binary |
| Standard body | IEC |
| Standard ref | IEC 61139-2 |

## Safety

- Supports safety-related applications up to SIL 3.
- Transmits safety-related data over IO-Link as a black channel.
- Allows simultaneous transmission of safety-related and standard data in mix mode.
- IO-Link Safety Masters can provide ports configurable for OSSD sensors.
- Safety function parameterization requires a permanently assigned, approved Dedicated Device Tool for the device.
- Standardized as IEC 61139-2.

## Study notes

- IO-Link Safety uses IO-Link as a black channel for safety-related data.
- Designed for IO-Link point-to-point communication; described as simpler than corresponding fieldbus safety protocols.
- IO-Link Safety Masters take over implementation in higher-level systems.
- Master ports can always be configured for IO-Link, enabling mixed standard and safety applications.
- Safety Masters can offer ports configurable for OSSD sensors for migration from conventional technology.
- Safety Devices may be operable with OSSD as well as IO-Link Safety.
- Suitable for sensors, actuators and mechatronic components.
- Mix mode transmits safety-related and standard data simultaneously.
- IODD is used for parameterization and integration.
- A Dedicated Device Tool is used for parameterizing safety functions; DTI is a standardized software interface.

## Sources

1. [IO-Link Safety: Reliable Point-to-Point Communication](https://io-link.com/technology/safety) (accessed 2026-10-25)

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