EtherCAT guarantees sortation equipment resiliency – it’s time to learn how
In retail, parcel, and beyond, sortation equipment is mission-critical for fulfillment operations. These systems efficiently sort and route products or parcels to specific locations within the distribution or fulfillment center, based on predefined criteria. Here, ultra-fast and flexible communication makes all the difference in reliably sending parcels to their destination – on time and at high volumes.
As the leading fieldbus technology in intralogistics overall, EtherCAT seriously enhances material handling performance. Sortation equipment, in particular, benefits from the unique advantages of EtherCAT.
Modern distribution and fulfillment centers rely on various types of line or loop sorters, with other variants also available. You can further classify these as pouch/hanging garment, bomb-bay, sliding shoe, cross-belt, tilt-tray, and belt sorters. All sorters share a common attribute: like basic conveyors, they feature a linear design. This creates unique challenges for most industrial Ethernet protocols, which rely on the Internet Protocol (IP) and switches.
But there are other challenges. Network diagnostics, cybersecurity, and openness – not to mention machine safety – all impact how efficiently your sorters operate. Let’s explore these core challenges and how EtherCAT can help you overcome them.
Why you need to ditch the switch
Switch-based systems may have real-time characteristics, but cannot be deterministic. Why? Switches have inconsistent delays as Ethernet frames pass through. That’s true even for very expensive managed switches. This inconsistency of measured time undermines determinism. Hence, the time it takes for a frame to travel through a switch-based network will vary with each scan.
In a line topology, delays through the switch port of fieldbus devices – such as I/O modules, valve manifolds, MDR (motor-driven roller) controllers, or drives – become exponentially more problematic. For example, the developers of other Ethernet-based fieldbus protocols recommend no more than eight fieldbus devices in a straight line on a PROFINET or EtherNet/IP network. Just eight devices in a line on the switch-based systems can add 1 millisecond of accumulated delay to the update rate.
The result of this switch-based approach is limited system flexibility, modularity, and diagnostics. On top of greater hardware costs, you’ll see increases in installation difficulty, commissioning time, and maintenance complexity. The lag from switch-based fieldbuses and their associated PLCs can hobble throughput and sort accuracy. The larger the system, the greater the issues. For this reason many sortation equipment suppliers are forced to fall back to a legacy style control system approach where devices are wired back to a central control cabinet or consider a multi-protocol approach that helps overcome these typical ethernet fieldbus limitations.
In contrast, modern machine designs have long shifted from hardwiring sensors and other devices back to a central control cabinet. Instead, they utilize a fieldbus to distribute I/Os and drives closer to sensors and motors, shrinking control cabinet and cabling requirements. In these architectures, EtherCAT offers an ideal industrial Ethernet option, precisely because it needs zero switches.
Satisfying the need for speed and synchronization
The EtherCAT industrial Ethernet system conforms to the OSI (Open System Interconnection) Model. But it operates at Network Layer 2, which isn’t based on IP (Internet Protocol). And it doesn’t utilize switches like PROFINET or EtherNet/IP. That’s a major advantage for sorters and other Intralogistics equipment. Since this equipment uses a linear architecture, a line topology is ideal – if not mandatory. EtherCAT supports line topology with no delay and nearly infinite scalability.
In addition, EtherCAT is deterministic. The system guarantees predictable timing behavior every update scan with cycle times as low as 31.25 microseconds and accuracy up to an incredible 100 nanoseconds. This incredible speed gives sorters precise timing and synchronization to ensure system efficiency. More accurate controls also improve the system mechanics, eliminating common mechanical failures, such as pin breakage on sliding shoe sorters.
The benefits of EtherCAT don’t end with system performance. Flexible selection of topology, including line, tree, star, and drops, adds to EtherCAT’s advantages. As sortation equipment continues to keep pace with e-commerce, the limitations of other fieldbus protocols mean they struggle to scale. EtherCAT, on the other hand, supports up to 65,535 devices on a single network branch or segment, and multiple segments out of a single automation controller.
EtherCAT’s cable redundancy ensures that communication continues uninterrupted should a cable or device fail anywhere in the network. Implementing this redundancy simply entails connecting both ends of the network to the PLC, which is natural for loop sorters and requires one extra cable for line sorters. When the issue is resolved, the system automatically communicates as normal from the main segment.
The sheer size and performance you can achieve with one EtherCAT network means you have practically limitless growth opportunities for the future. With the wide range of machine-mountable field devices from Beckhoff, you can install everything from MDR control and drive technology to valve manifolds and integrated functional safety right on the sortation equipment, no cabinets needed.
Safety over EtherCAT is the safe choice for sorters
Machine safety only increases in importance. New safety standards emerge at a rapid clip. So do requirements from end users who hold the liability for accidents at their facilities.
The Safety over EtherCAT (FSoE) protocol enables machine designers to meet rigorous requirements for safety without a separate safety PLC or hardwired safety system. Instead, safety frames are communicated across EtherCAT via a “black channel” approach. This provides a low cost and extremely flexible safety system that can meet safety ratings up to SIL 3, CAT 4.
Safety information across the EtherCAT network offers another advantage: it enables quick diagnosis of the safety system by the PLC, and even on the HMI. This allows, for example, operators and maintenance staff to quickly identify which e-stop or safety device along the sorter has been triggered, rather than sacrificing uptime to visually inspect each one.
Beckhoff makes the FSoE functionality available in a wide range of TwinSAFE solutions. TwinSAFE safety input boxes with IP67 protection can be incorporated anywhere along the sortation equipment and connected to the EtherCAT network trunk. Further e-stops and other safety sensors can easily be connected to these I/O blocks at any point in the machine’s life cycle.
EtherCAT-equipped drive technology can also harness standard safe motion functions without requiring any further safety I/Os or typical hardwiring. Beckhoff offers 17 TwinSAFE motion functions – for safe stop, positioning, acceleration, speed, and brake functionality – with different options available across our servo, stepper, and VFD products.
Instead of the traditional approach to safety where all safety logic is centralized, a Beckhoff safety system with FSoE permits distributed safety logic. This means the sortation system can be further modularized with various safety zones on the same EtherCAT network.
Built-in advantages for diagnostics and cybersecurity
EtherCAT’s built-in diagnostics capabilities are unrivaled and ensure easier maintenance and increased uptime. With Beckhoff, no proprietary backplane protocols are used for the I/O racks, instead the entire system communicates directly via EtherCAT. As a result, common network problems such as a loose cable or types of interference can be detected often before a system fault by watching increasing CRC errors as a preventative maintenance measure.
The status of each device, including CRC errors, is always visually available in real-time. It can be incorporated into the HMI via TwinCAT HMI software and a freely available API that is automatically created when the network is configured. Any issue with the EtherCAT network can be easily and quickly identified.
EtherCAT also supports the transmission of large amounts of data without impacting network performance. As a result, further preventative maintenance measures can be included on the sorter via TwinCAT Analytics and TwinCAT Machine Learning. Further sensors can be easily adapted to the EtherCAT network to support advanced condition monitoring, power measurement, and other functions.
High-performance servomotors from Beckhoff add further predictive maintenance capabilities with the innovative Beckhoff Smart System Diagnosis (B/SSD). This functionality transfers precise measurement of vibration, humidity, and temperature directly in the motor across the EtherCAT network for statistical evaluation in the Beckhoff PLC for highly effective predictive maintenance.
In my many meetings with end users, I’ve also consulted on their rapidly evolving requirements for hardening the fieldbus. These efforts are taking center stage. IT departments are no longer just concerned about hardening the controller – they also want to provide cybersecurity across the fieldbus and safety systems to limit liabilities and downtime from an attack vector targeting such systems. Here, too, EtherCAT delivers on cybersecurity.
First off, EtherCAT’s independence from the Internet Protocol (IP) is a major plus. Malware typically travels across IP, so EtherCAT instead uses a unique EtherType adding to its cyber resiliency. This is just one of the many reasons why EtherCAT is cybersecure by design. A further benefit is that the EtherCAT network is automatically configured so long engineering hours are no longer devoted to the menial work of configuring IP addresses.
Open to options: a vast array of possibilities
A final important EtherCAT benefit is its complete system openness. The recent global supply chain crisis has made everyone painfully aware of how fragile the world’s supply chain can be. A key protection against many supply chain problems is an open, standards-based system.
Beckhoff has worked diligently to strengthen its own supply chains and second-source strategies to ensure availability of I/O terminals and other devices. In addition, the EtherCAT Technology Group (ETG) boasts more than 8,000 member organizations and over 4,000 registered EtherCAT device manufacturers making it the largest fieldbus and industrial Ethernet organization globally.
EtherCAT is the most open fieldbus on the market and supports the integration of almost any type of sensor, drive, or other device via any of the open fieldbus protocols supported. Both modern industrial Ethernet protocols such as PROFINET and EtherNet/IP as well as legacy protocols such as PROFIBUS and DeviceNet are supported, and even protocols such as IO-Link, CANopen, ASi, Modbus, Ethernet TCP/IP, and others are all covered.
From performance to safety, footprint reductions to cybersecurity, EtherCAT and the comprehensive technology portfolio from Beckhoff deliver the ideal automation platform for sortation equipment.
Want to learn more about how EtherCAT and Beckhoff’s control products can generate compelling results in your sortation equipment? Contact your local Beckhoff sales engineer today.
Doug Schuchart is the Global Intralogistics Manager at Beckhoff Automation
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