Previously, if larger data volumes had to be read out from IO-Link devices, e.g. for diagnosis purposes, such as images from optical sensors or long-term progressions, this was only possible through proprietary means. The BLOB profile developed by the IO-Link community now provides an option for segmenting the larger data volumes and then transferring them through the existing ISDU (Indexed Service Data Unit) communication mechanism in a controlled manner. This involves standardized transfer of large data volumes (typically several kilobytes), so-called BLOBs (Binary Large Objects), from the IO-Link device to a host controller or vice versa (bidirectionally). The host controller can be a PLC or computer tool, for example.
The trick is that IO-Link is used here “only” as a data channel. The actual segmentation and flow control takes place in the device, or in the PLC or the PC program. The great advantage of this is that the IO-Link master and the field level are not affected. This means that no modification of the existing system is necessary, and devices that support BLOB transfer can be connected to any existing IO-Link application.
On the host side, the BLOB process can be implemented in a function block for the PLC, for example. This makes sense especially if the PLC program requires the data for further processing, e.g. when reading out RFID tags with IO-Link RIFD readers or reading out collected protocol information from a device for diagnosis. If the data is to be used only for service purposes, it can also be read or written via a normal USB master and special software, for example.
This creates options for reading even large data packages, such as can arise in image recognition, from the final meters in the field for detailed data analysis. This is a further critical step for future Industry 4.0 applications.