IO-Link data packets contain parameter data of an IO-Link slave device that is acyclic and is only transferred when read or write is requested by the machine controller. Having parameter data available on a device is not new or groundbreaking; however, the main advantage of IO-Link parameter data is that it is directly accessible by the machine controller, and it is dynamic, meaning you do not have to take the device offline to change its parameters or configuration. Parameter data determines how flexible or configurable an IO-Link slave device is. Its content will be different from device to device and manufacturer to manufacturer, a differentiator when choosing the right device for your application. We all know that not all IO-Link devices are created equal.
So how can you take advantage of parameter data?
Automatic machine configuration
Imagine if your machine could automatically configure itself upon first power-up? Yes, it is possible. Because IO-Link parameter data is accessible by the machine controller, i.e., the PLC or PAC, one can write a routine/program that first verifies the correct device is connected to the correct port of the IO-Link master, request a parameter read, compare the parameter content to the desired configuration in the program, and overwrite the current device parameter set if necessary. Why would someone do this? Well, if you are an OEM machine builder building ten of the same machines for one end customer, it would be a worthwhile investment in programming development to have IO-Link devices configured automatically. This method would eliminate the need for manual machine parameterization and result in cost savings. Examples of typical configuration would be changing the pin assignment of an IO-Link freely configurable discrete input/output hub as an input or an output, machine home position or offset of an IO-Link linear transducer, set points of an IO-Link pressure transducer, set points of an IO-Link laser distance sensor, and so on.
Recipe change
Another way to take advantage of IO-Link parameter data is to have the machine controller automatically change device configuration based on recipe change. This would eliminate the need for an operator to manually change device parameters, thus saving time and minimizing human error, especially if the device is not easily accessible by a human.
Maintenance
Having direct access to device parameters by the machine controller also enables OEMs to simplify their machines’ serviceability. For component replacement, all the maintenance personnel would have to replace a damaged device with a new device and walk away, eliminating the need for specialized training, software, or hardware.
Some manufacturers add special functions to their IO-Link masters to enable automatic backup and restoration of IO-Link slave device parameters, making replacement of components as easy as plug and play. This function would eliminate the need for OEMs to create custom programs or logic in their PLCs to restore parameter sets on a device automatically.
How to
So how would I do this? Because parameter data is accessible by the machine controller, implementation of auto configuration differs based on what brand of controller you are using. I will mention a few of the most popular.
- Allen Bradley – For the Allen Bradley family of PLCs, you would use an explicit instruction to read and write IO-Link device parameters.
- Siemens -For the Siemens family of PLCs, you would use a standard function block named “FB_IOL_CALL”.
As you can see, every PLC or machine controller manufacturer and their flavor of IDE (Integrated Development Environment) will have their unique way of accessing IO-Link device parameter set. It is best to consult with both manufacturers and review IO-Link devices and PLCs to better understand how to set the read and write parameters of an IO-Link slave device.
Conclusion
Having direct access to device parameters and being able to change them without taking the device offline or needing special software or hardware, and implement it at a device level is game-changing. It opens doors for time and cost savings in design, integration, operation, and serviceability of machines. It is different from what we are used to, so don’t be afraid to think outside of the box and jump in with both feet.
Great article Adis. It clearly explains some of the most popular ways to take advantage of the the power of IO-Link. The ability to manipulate device parameters “on-the-fly” will transform our machines going forward.