Upgrading the Wire
The role of connectivity in industrial automation has changed over the years. In the past, sensors and actuators were connected to PLCs, resulting in “islands of automation”. Today, IIoT ensures that the data flowing is also captured and analyzed, making it easier to find efficiencies and improvements as the worlds of IT and OT merge. While current loops of 4–20 mA delivered process data over large distances in the past, newer physical layer technologies, such as EIA-485, Modbus, ASi-5, IO-Link and CAN, have largely displaced them. These also provide support for bi-directional communication, more straightforward installation and higher bandwidth when combined with PROFIBUS or DeviceNet protocols.
However, today’s industrial machines generate increasing amounts of data or have multiple nodes requiring real-time control that is accurate to the millisecond. Both of these issues can be solved by increasing the bandwidth, so naturally, Ethernet is a possible solution. However, while its bandwidth has steadily increased to support IT needs, Ethernet has lacked the bandwidth reservation and hard real-time guarantees required by industrial automation.
Despite this, automation system providers have leveraged Ethernet’s high bandwidth to deliver these real-time requirements. By modifying the software stack, response times for 100 axes under 1 ms with jitter below 1 ms are possible at data rates of 100 Mbits/s. Industrial Ethernet now commands a 66 percent market share, with EtherNet/IP, OPC UA, PROFINET and EtherCAT® making up more than two-thirds of that.
Learn More About EtherCAT®
EtherCAT has established itself in control and regulation applications. Thanks to the simple processing of data telegrams as they pass through daisy-chained slaves, the microprocessors (MPUs) in PLCs can focus on their control tasks rather than on data communication. Devices such as the LAN9255 simplify their integration into drives by offering two 100BASE-TX full-duplex EtherCAT device controllers alongside SAM E53 MPUs that feature powerful 32-bit Arm® Cortex®-M4 processors. Rapid prototyping is straightforward thanks to an evaluation board and configuration file that generate the EtherCAT Slave Stack Code (SSC).
Industrial networks also benefit from additions to the IEEE 802.1 and 802.3 specifications that build in guaranteed end-to-end latency, known generally as Time Sensitive Networking (TSN). These are implemented in layer 2 (Data Link) rather than in the application layers as implemented by PROFINET, meaning a matching Ethernet is also needed. The Linux-capable ATSAMA5 and ATSAMA7G45 are ideal candidates, especially when targeting power-over-data line (PoDL) end device designs. IP blocks supporting IEEE 1588 v2 are also available for the PolarFire range of FPGAs. Otherwise, classic embedded applications supporting TSN can be implemented using the SAME70 or SAME53/54 families of microcontrollers.
Microchip also offers a range of gigabit TSN-enabled industrial Ethernet switches with the VSC754xTSN and VSX755xTSN devices, or four 100BASE-T1 ports with the LAN9370. To achieve nanosecond-accurate IEEE 1588 timing, dedicated clock management is required. Network synchronizers, such as the ZL30802, and multiplier and frequency synthesizers, such as the ZL30251 and ZL30267, generate ultra-low jitter clock trees with their fanout buffers in small footprint packages.
Another development is in the physical layer of Ethernet. Most will recognize the bundle of eight twisted-pair cables connected to an RJ45 connector. This could be overkill for industrial sensors, which is why Single Pair Ethernet (SPE) developed. Thanks to changes at the physical layer, 10 Mbits and more are possible in half-duplex multi-drop and full-duplex networks using a single, unshielded twisted pair while conforming to EMC standards and remaining unaffected by noisy electrical environments. It also makes for lighter, more flexible cabling when coupled with the smaller, more compact M8 connectors. Applications range from sensors and actuators to cameras and robotics.
Learn About Single Pair Ethernet (SPE)
Applications range from sensors and actuators to cameras and robotics.
Cost-effective and low-power single-chip transceivers are available. These include the LAN8670/1/2 that supports 10BASE-T1S half-duplex point-to-point over segments of at least 15m, or multi-drop mixing segments up to at least 25m in length with up to at least eight PHYs, as defined by the standard. In addition, power over the data lines can deliver up to 60W or 500 mW in Zone 0 intrinsically safe applications.
The different versions of the LAN867x transceiver provide support for the MII or RMII interfaces and the Serial Management Interface (SMI) offers standardized access to the configuration registers. Thanks to the PLCA collision avoidance feature, you can achieve high-bandwidth utilization and keep RF emissions in check to fulfill EMC and EMI requirements.
Automation technology in our manufacturing facilities is growing in capability, placing more demands on the electronic systems used. More robots and vision systems demand higher bandwidth for data and tighter tolerances and guarantees for data delivery to achieve accurate control. Silicon devices that support these industrial networking technologies, along with development boards and software drivers, support development teams as they address the needs of these demanding applications.
Factory Automation
ATSAME53
Ethernet Switches for TSN
