Ethernet encoders: Adding useful features to their original function
Improvements need to be based on measurements. This is the only way that lasting and reliable enhancements can be made to processes and that the high availability levels of well-established procedures can be guaranteed in the long term. Precise measurements accompanied by an equally precise analysis of the data are an essential feature of Industry 4.0. The latest generation of Ethernet encoders from SICK opens up new opportunities for obtaining different measurements in addition to the data related to tracking movements. This new information can be used for effective status monitoring, for example.
Smart automation solutions do much more than simply connecting individual components. In the case of mechatronic systems, the whole had to be more than the sum of its parts. However, the crucial factor for Industry 4.0 is the performance of cyber-physical systems. What is the result of this for encoders, which are the central monitoring components in automation solutions? The Ethernet communication options of the SICK devices and the TCP/IP connection in the form of a node in an overall network open up new opportunities. These go far beyond the original automation functions of the encoders.
More precise counting for more accurate results
It would be very useful to know how often a motor has turned, instead of only being given information about the period when a voltage is applied to it. Obtaining actual figures about the number of times a machine component has changed its position during the production process could also be valuable. In both cases, the encoder first has to perform its original function of precisely identifying the position of components and passing this information to the controller or a servo converter within a closed control loop. However, the cycle frequency of the components provides important information about their service life in the long term. These counted data are a much more useful solution than simply checking the date of manufacture and installation of machines when evaluating the condition of the production facilities.
The power-up times only offer limited information about the service life, the ageing of operating materials and the wear levels, in particular in the light of the fact that machines are rarely if ever, disconnected from the power supply and go into standby mode when not in operation. This new approach becomes particularly useful when a machine’s components have different service lives because it allows individual parts that have reached the end of their life to be replaced during regular or preventive maintenance.
The motion timer function of SICK’s Ethernet encoders makes it possible to record the encoder’s operating hours accurately. While the operating time meter in power-up mode only provides information about the number of the hours when the encoder is live, the motion timer records the periods when the encoder is moving. It also counts the number of times the encoder is powered up. This means that maintenance can be carried just when it is needed, which helps to prevent downtimes. No additional systems are required to achieve this.
Another possible scenario in which Ethernet-based encoders can improve the availability of production facilities is temperature monitoring. If temperature sensors are used in processes, their primary function is to measure the process temperatures or to protect components such as motors from shutting down because of the heat. This information allows conclusions to be drawn out about the temperature profiles of the entire process and when combined with other parameters, can be used for application-specific condition monitoring.
More options without accessing the controller
The appeal of this solution lies in the fact that one single encoder can supply the traditional process data, such as position and speed, via industrial Ethernet protocols and, at the same time, can make use of additional functions and configurations via TCP/IP. For this reason, SICK fits its Ethernet encoders with a dual port switch. Separating the machine function from the overlying status monitoring process opens up the possibility of performing these higher level tasks independently, regardless of the possible restrictions imposed by a machine controller that may be inaccessible.
In practice, intelligent SICK encoders can be configured to meet the requirements of individual applications or of specific conditions in the areas where they are used. By setting the limits and thresholds individually and directly in the encoder via the software system in the PLC or via a web server and a browser-compatible end device, the correct measuring range can be specified for every application with a high level of standardisation. When the specified position, speed and temperature thresholds are reached, the encoder automatically sends a signal via the Ethernet connection to indicate that an investigation must be carried out. As already explained, this function operates independently of the machine controller.
Communication via the well-established industrial Ethernet protocols – Ethernet I/P, EtherCAT and PROFINET – allows the process data to be converted to the most suitable mathematical and physical units and evaluated accordingly. As the data is imported into control or MES systems in the right format, no further calculations are needed to produce the required figures.
Customised encoders – another aspect of Industry 4.0
The adaptability of SICK’s encoders also extends to their connectivity, in particular about plug options, mechanical supports and cable lengths. At SICK, customising is based on a sophisticated variant management system with flexible production options down to batch size 1. This closes the loop to Industry 4.0, which is an industrial revolution that emphasizes individualised large-scale production.