IO-Link Technical Description

Basic Data Types for IO-Link Communication

Process data (Cyclic Communication)

Data is communicated cyclically and can be obtained without a PLC program.
Process data size is determined by the device, with 0 to 32 bytes available. Ex.) Distance data for displacement sensor, temperature data for thermometers, flow data for flow sensor, etc.

Service data (Acyclic Communication)

This information includes parameters, identification data (model, serial number, etc.), and diagnostics.
These information can be communicated acyclic by request of the IO-Link Master.
Device data can be written to and read from the device.

Event data (Acyclic Communication)

If an error such as a short circuit, overheating, or contamination occurs or is predicted to occur in an IO-Link device, the master can be notified without interfering with process data transmission.
(Event details vary depending on the IO-Link device)
As for wire break between the IO-Link Master and the device, it can be detected if there is no response from the device after a retry from the master.

Fastest Cycle Time for IO-Link

The three types of fastest cycle time for IO-Link are as follows.

・ COM1: 4.8 kbps, transmission at a maximum speed of 18 ms
・ COM2: 38.4 kbps, transmission at a maximum speed of 2.3 ms
・ COM3: 230.4 kbps, transmission at a maximum speed of 0.3 ms

The above values are the fastest cycle time of IO-Link Master. In general, it is automatically set to match the fastest cycle time of the connected device.

Standard Sensor Cable (3-wire unshielded cable)

Standard sensor cables used in the past can be used for the cable.
A 3-wire unshielded cable, including the connecting communication line, can be used, eliminating the need for a dedicated cable.

IODD File

The IODD (IO Device Description) that defines IO-Link device information is provided by each IO-Link device manufacturer. The following data is stored in IODD file.

- Device data
- Identification data, process data, and diagnostics
- Manufacturer's Logo
- Communication Properties

*Data stored varies by manufacturer and model.

Index List

A list of where and what data is allocated to the IO-Link device.
This is mainly a list of data you want to retrieve from the device or check when setting it up.

IO-Link Complete Guide