IO-Link Debugging in Development and Test

Anyone developing or testing IO-Link devices will eventually face the same two questions:

1. What does the physical IO-Link signal actually look like?

2. What is happening on the communication and protocol level?

In practice, both levels need to be analyzed. However, this is often done using improvised solutions. Cables are cut, custom adapters are built, or measurements are performed only once under non-reproducible conditions. This costs time and rarely scales well.

For signal-level analysis, clearly defined access points are required.

• This is especially important when investigating:
• signal quality
• voltage levels and edges
• noise and disturbances
• timing on the physical layer

Such analyses typically require direct connection of oscilloscopes or logic analyzers.

The IO-Link Signal Exposer is a simple helper board designed exactly for this purpose.
It is inserted between IO-Link master and device and provides defined test points for all relevant signals.

Typical characteristics:

• two M12 connectors (master / device)
• dedicated test points for measurement equipment
• LEDs for quick visual signal indication

This allows IO-Link signals to be measured without cutting cables or building custom adapters. Measurements remain reproducible and can be repeated at any time under the same conditions.

In many cases, the signal shape alone is not sufficient. Sporadic errors, timing issues, or unexpected states often occur only occasionally and cannot be reproduced in a lab setup.

The IO-Link Spy addresses this challenge by enabling passive analysis of IO-Link communication during operation.
It is simply clipped onto the IO-Link cable and taps the signal contactlessly, without interrupting or influencing communication.

Captured data is transferred to a PC and can be analyzed using dedicated software, including:

• byte- and frame-level decoding
• protocol-level analysis
• application-level decoding based on IODDs
• timing analysis of requests and responses

This approach is especially valuable for rare or intermittent issues, as the machine or system can continue running while data is recorded.

The Signal Exposer and the IO-Link Spy address different layers, but complement each other in everyday debugging:

• IO-Link Signal Exposer
  Access to the physical signal, oscilloscope and logic analyzer measurements, reproducible signal-level tests.

• IO-Link Spy
  Analysis of IO-Link communication during operation, particularly useful for sporadic or timing-related issues.

Together, they enable a consistent debugging workflow from the electrical signal up to interpreted IO-Link communication.

The combination of both tools is particularly suited for:

• IO-Link device development
• application testing and validation
• troubleshooting sporadic communication issues
• analysis of signal quality and timing
• training and demonstration of IO-Link behavior

Efficient IO-Link debugging requires visibility on both the signal level and the communication level.
With the IO-Link Signal Exposer and the IO-Link Spy, two practical tools are available that avoid improvisation and enable reproducible, structured analysis in development and test environments.