Sensors featuring IO-Link open up new possibilities of communication with automation systems. after successfully integrating photoelectric proximity switches or magnetic cylinder sensors from SICK into various applications, well-grounded feedback from practical operations is now available on the question as to what the user gets out of it.
Two machines, two processes, one sensor technology
When using IO-Link photoelectric proximity switches from the WT18-3 series in a carton packaging machine, the end user can fully automatically adjust the sensors to the geometrical properties of the cartons in accordance with the respective packaging batch to be processed by using either the control panel or the stored job data. To this end, upon start-up of the machine, an exact adjustment of the scanning distance of the photoelectric switches was carried out for each format to be processed, using the teach field on the touch-screen machine terminal. During operation, the optimum parameters, e.g. the scanning distance of the sensor, are retrieved from the automation system, transferred to the sensors, and, if required, displayed on the panel. Mechanical readjustment of the sensors becomes redundant – moreover, the settings of the WTB18C-3 are 100 percent reproducible from one task to the other and thus reliable. Eventually, the communication capability of the IO-Link sensors – in this case embedded into the existing control and Profibus DP design of the carton packaging system – has simplified the operation of the machine to an unprecedented extent.
With respect to the operation of a wood-processing machine, the focus of attention is on minimizing batch-related make-ready and adjustment times. Prior to feeding the wood products in, hydraulic actuating drives are brought into a position that allows collision-free feeding of different sizes. In this context, the maximum travel of the actuating drives is significantly greater than usually required in process technology.
With the WTB27-3 photoelectric proximity switches, it was possible to minimize the respective travel required, thus saving valuable set-up time. In order to guide the actuating drives into the optimum ”waiting position” in the respective instance, the machine controller uses the IO-Link to read into each photoelectric proximity switch the very value that it was taught at start-up for the respective format and that was saved in the controller. After each format change, the value in the photoelectric proximity switch is overwritten by the new value. As soon as the photoelectric proximity switch detects the actuating drive in the desired distance, it is stopped.
More flexibility, more availability
Both in the packaging machine and in the woodworking machine, IO-Link renders the processes controllable in a flexible way, while at the same time increasing machine performance. thus, the technology offers end users crucial added value as compared to ”traditional” sensor integration. Thanks to IO-Link, it is possible to optimize the availability of the entire machine, e.g. by preventive maintenance. Both in the packaging machine and in the woodworking machine, the photoelectric proximity switches indicate the degree of their pollution independently. At this time, the sensor function is still guaranteed unconditionally – but the information allows maintaining the facility during an operating break, thus preventing downtimes caused by unplanned machine stoppages. Conversely, for scheduled equipment maintenance, one can poll all of the connected IO-Link sensors via the automation system. In case of a malfunction, the machine operator is able, via this diagnostic function, to get an idea of the possible causes from a central location. All of the important data, e.g. signal quality, the status of the switching output, or a possible short circuit, are displayed on the machine’s operating panel. Thus, many errors can be fixed even by operating personnel that has no special knowledge concerning automation.
The upshot: for users, IO-Link opens up new opportunities of increasing efficiency and productivity as well as reducing costs. SICK is perfectly suited as a partner for this purpose – on the one hand, because even today, a wide variety of IO-Link devices and integration technologies are available, e.g. photoelectric proximity switches, automation light grids, magnetic cylinder sensors, or IO-Link field modules; on the other hand, because all of the sensors and components from SICK meet IO-Link specification 1.0, thus ensuring full interoperability with devices from other manufacturers.