IO-Link is a brand name for a communication interface between intelligent sensors or actuators and automation systems. This interface was specified at a meeting of the top suppliers of automation technology. A standardization was created according to the IEC 6113-9 standard.
The benefits of an IO-Link system are the savings in materials and working time, as well as simpler wiring, simpler replacement of devices, as well as advantages in parameterization, remote diagnosis and error identification.
Until now, to get a signal from a sensor, a PLC was mounted on the control cabinet and an analog board group was set, which was wired to the sensor. It became problematic when you had to set several sensors and the control cabinet was also far away. An IO-Link system should solve this.
The structure of an IO-Link system consists of: CPU, IO-Link master, IO-Link device (sensors, for example).
The communication between CPU and IO-Link master can take place via different interfaces, such as Profibus and Profinet. The IO-Link master requires an external power supply (24 V DC). The sensors are connected to the master via IO-Link. This is therefore not a fieldbus but a point-to-point communication.
An IO-Link master can be installed directly in the field. Due to the increased degree of protection, a control box is no longer required. There are many ways to communicate with the CPU. The sensors can now be connected to the IO-Link master wirelessly, if necessary using a 3-wire connection. Bidirectional communication enables efficient parameterization as well as extended diagnostics. The speed can be explained by the three communication speeds (4.8kbaud, 38.4kbaud, 230.4kbaud).
Now information can be exchanged via a serial protocol. Among other things, the log consists of measured values, diagnostic data and configuration parameters. What is special is that there is the possibility of an early warning system. Changes in the process are perceived and communicated. In this way, an adjustment can be made in advance, instead of after a defect, as was previously the case.
Example pressure sensor A-1200
A good example is the A-1200 pressure sensor from Wika. This can be flexibly programmed via IO-Link and can be used for pressure monitoring as well as for process control. It has an integrated diagnostic function for monitoring to ensure these precise measurement results. Since a digital signal is used, the A-1200 can also be configured externally.
The log is presented in tabular form with very clear error information.
|| Sensor is defective - overpressure - underpressure - overtemperature - undertemperature
In this way you are very directly made aware of process changes. Process failures that would occur in the event of a defect can now be avoided with a timely warning. The same applies to temperature measurement in the sensor electronics, which is intended to prevent deviations in the measured values due to temperature changes.
Other information recorded by the A-1200 is minimum and maximum values of pressure and temperature. This data has been recorded since the device was commissioned. There is also an operating hours counter.
All of these recordings are ongoing.
If the device is reset, all parameters will be overwritten.