Enabling Industrial Connectivity - The IO-Link State Machine: Part 2 of 2

The Time-Critical Nature of IO-Link

IO-Link is a transformative force in factory automation, as highlighted in Part 1 of this series. It is enhancing communication and simplifying integration with its user-friendly, plug-and-play bidirectional communication interface for sensors, actuators, and other industrial edge applications. However, this simplicity and ease of use is primarily enjoyed by the end user.  Designers of these devices face several challenges in implementing a fully compliant IO-Link interface, one of which is the time-critical requirement that the protocol demands. 

Timing Requirements in Practice

IO-Link can operate at 3 different communication speeds: COM1 (4.8kbaud), COM2 (38.4kbaud) and COM3 (230.4kbaud). Additionally, the IO-Link standard requires that the protocol be given top priority among the system microcontroller’s tasks and that an IO-Link device (i.e. sensor or actuator) must service all Master requests.

This is where the timing complexity comes in. An IO-Link device must respond to a Master request within 10 bit-times (t_A), which at COM3 speeds can be as short as 43µs. This requirement often leads to the need for a faster processor or an increased microcontroller clock rate.

Integrated IO-Link State Machine

To alleviate this timing burden, ADI has developed an integrated IO-Link State Machine in its latest IO-Link device transceiver, MAX22516. This state machine autonomously manages the time critical responses to the IO-Link master, allowing the application microcontroller to prioritize measurement data or other tasks. This is possible up through COM3 speeds and passes all IO-Link compliance tests. Additionally, it features an on-board buffer which enables the microcontroller to load updated Process and On-Demand data when optimal. The IO-Link state machine then autonomously provides that information on Master request.

Where to Leverage ADI’s IO-Link State Machine

1. Upgrading Communication Speed

The IO-Link state machine can easily upgrade existing applications from COM2 à COM3 speeds without major software efforts or upgrades to the microcontroller capability

2. Time-Critical Sensing & Monitoring

The autonomous responses free up the application microcontroller to prioritize time critical measurements over the IO-Link communication requirements. This can be specifically useful in applications such as ultra-sound sensors and distance sensors

3. In-House Software Development Efforts

By managing the time critical tasks, Analog Devices, Inc. (ADI’s )IO-Link state machine simplifies the overall software complexity, making it easier to enable in-house IO-Link stack development

4. New Users of IO-Link

ADI has paired the IO-Link state machine with two rapid prototyping reference designs, MAXREFDES281 & MAXREFDES284 to drive faster time to market, enable new feasibility studies for IO-Link devices, and simplify software efforts.

Three Key Takeaways

ADI is the market leader in IO-Link for a reason.

1. The IO-Link state machine offers our customers more capabilities, removes barriers, and enables the highest level of performance for sensors & actuators.
2. The globalization of Industry 4.0 has catalyzed the adoption of IO-Link and made it a key technology for the next generation of industrial automation.
3. ADI’s products are paired with expansive design resources and highly knowledgeable support staff to enable you to quickly and efficiently enable IO-Link in your specific application

www.io-link.com

See all the blogs in the ADIOLINK series.