Chris Jones, managing director at Micro-Epsilon UK, discusses the growing importance of EtherCAT in enabling the latest laser displacement sensors to transfer measurement data in real time in automated industrial environments
In industrial automation technology, there is a growing trend towards replacing existing first generation fieldbuses with industrial Ethernet. As a result, Micro-Epsilon is integrating new, real time Ethernet technology into many of its laser displacement sensors and controllers. Unlike conventional bus systems that require lots of installation effort, industrial Ethernet is faster and easier to integrate, which explains why this technology has gained widespread acceptance in many industrial manufacturing environments.
Due to its larger bandwidth and real time communication capabilities, sensors and controllers that are connected via Ethernet enable extremely high speed data transfer, simplified read-out and analysis of process and measurement data, as well as location-independent configuration of the sensors. Unlike conventional analogue output signals that suffer from inherent ‘noise’ on the output circuit due to grounding, electrical resistance from connectors and cable quality, measurement data sent via digital networks does not degrade even long sensor cable lengths. Any increase in ‘noise’ on a circuit effectively reduces the measurement resolution and results in reduced accuracy of measurements.
In addition, manufacturing processes are becoming higher speed and more automated and so these industrial networks require sensors and measurement systems that support these faster, dynamic processes. As a manufacturer of precision sensors, Micro-Epsilon is at the forefront of developing sensors and controllers that cater for these future industrial requirements.
In recent years, EtherCAT has established itself within the market as a communications standard (protocol) that can offer true real time capabilities in automation technology. In line with this, Micro-Epsilon has developed sensors and controllers with EtherCAT capability, enabling them to be smoothly integrated into existing control and automation networks.
EtherCAT explained
EtherCAT is a fully Ethernet-compatible and truly ‘open’ standard. EtherCAT technology overcomes the system limitations of other Ethernet solutions. The Ethernet data ‘packet’ is no longer received, then interpreted and copied as process data at every connection. Instead, the Ethernet frame is processed ‘on the fly’. The newly developed FMMU (fieldbus memory management unit) in each slave node reads the data addressed to it, while the telegram is forwarded to the next device or sensor. Similarly, input data is inserted while the telegram passes through. This means the telegrams are only delayed by a few nanoseconds.
On the master side, very inexpensive, commercially available standard network interface cards (NIC) or any onboard Ethernet controller can act as the hardware interface. The common feature of these interfaces is data transfer to the PC via DMA (direct memory access). In other words, no CPU capacity is taken up for network access.
EtherCAT offers new heights in terms of network performance. Due to the FMMU in the slave nodes and DMA access to the network card in the master, the complete protocol processing takes place within hardware and so is independent of the run-time of protocol stacks, CPU performance or software implementation.
EtherCAT controllers
For many years, Micro-Epsilon has provided customers with displacement sensors that offer synchronous master-slave capability. However, EtherCAT now provides customers with genuine real time measurement performance, particularly in support of high speed processes and automated production technologies.
All new laser and optical sensors and controllers developed by Micro-Epsilon have EtherCAT protocol integration as standard, allowing integration with EtherCAT/Ethernet networks.
EtherCAT laser displacement sensors
Laser displacement sensors are also being equipped with Ethernet interfaces, allowing connectivity with EtherCAT networks. Micro-Epsilon’s optoNCDT 2300, for example, is a market-leading, self-contained laser displacement sensor, which requires no separate controller and which provides an extremely high measuring speed of up to 50kHz and resolution of 0.0015 per cent FSO (Full Scale Output). The sensor is therefore ideal for high-speed dynamic applications such as vibration measurement and profile scanning of uneven, rapidly changing surfaces.
Micro-Epsilon UK
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