EtherCAT (Ethernet for Control Automation Technology) was originally developed by Beckhoff Automation, a manufacturer of PLCs (Programmable Logic Controllers) used in real-time control systems and industrial automation.
Today plctop.com will learn about EtherCAT with you in detail.
Why use EtherCAT?
Why can’t we simply use Ethernet to connect control systems? Ethernet is very fast. It’s not expensive. And it’s easy to do in today’s computer software tools. So what’s missing?
In the application cases on sending and receiving mail. On a day when only 100 messages have arrived, your message will quickly appear in your inbox. On days with lots of mail, it will take longer, but it makes no difference, right?
However, with control systems, time is an extremely important factor. Some time has happened and with as much resolution and time axis accuracy as possible. A factory automation control system is by definition a real-time system. Switching on and off requires very low latency. For example, you don’t want your emergency shutdown notifications mixed in with your gigabyte data backup stream – real-time notifications always take precedence.
But in a typical Ethernet system, there is no protocol to handle this – all data is essentially “equal”. This works well with office computers that share network bandwidth to access servers and printers, but is not suitable for real-time applications.
EtherCAT physical layers
The physical layer is the hardware that physically transmits data over the network. This is the core power, i.e. the “mechanical” level of the network.
The data link layer is where data is encoded into packets. The Ethernet implementation here is fine, and EtherCAT uses it. But then other layers known to Ethernet users such as Network layer (IP) and transport layer (TCP and UDP) were completely ignored by EtherCAT because it cares about cycle times.
EtherCAT is fault tolerant
If the output of the last node is not connected to the main node, the data is automatically returned in the other direction via the EtherCAT protocol. Timestamps are maintained.
This fault tolerance means that EtherCAT networks do not have to be arranged in a ring like the diagrams shown above, but can be configured in a variety of ways, including a tree topology. , ring topology, line topology, star topology, and even associative.
Of course, there must be a link between master and slave. If you power them off, they won’t work, but the bottom line is that the topology of the network is very flexible and fault tolerant to an exceptional degree.
Differences in “Ethernet” and “EtherCAT”
Ethernet and EtherCAT differ at layers above the physical and data link layers. Let’s look at the differences and then come to the conclusion that EtherCAT is suitable for real-time system applications:
In a typical Ethernet network at your office or home, many devices are connected at essentially the same level. Any device can send data over the network, and any device can receive data. The network may have a switch that connects it to an internet device to provide remote access over the internet.
This is very flexible but prone to data overload when multiple devices send or request large amounts of data at the same time. Time-critical messages can be slowed down or even blocked in extreme cases.
EtherCAT works in a very different way:
The EtherCAT MASTER device is the only device that is allowed to transmit data over the network! The master sends a string of data over the bus, eliminating Ethernet system data collisions and optimizing speed as a result.
These frames are received by the EtherCAT slave devices (nodes) to which it is sent. The slave devices process the data and re-add whatever is requested by the master and send the frame along with the next node in the ring.
What is the difference between EtherCAT and CANopen?
CANopen is a high-level protocol based on the CAN hardware bus. It also includes a specification for any device on the bus. While EtherCAT uses the two lowest layers (data and physical) of the Ethernet protocol, CANopen uses the two lowest layers of CAN OSI.
Leveraging existing and proven hardware by many manufacturers is a key advantage of CANopen. CAN was started as a way to reduce wiring in cars, but it has evolved over the decades to be used in almost every industry and thousands of applications, from industrial to aerospace. , energy, etc. Putting the high-level CANopen protocol on top of proven and trusted CAN hardware makes system deployment and development easier than ever.
CANopen provides a high degree of interconnection and thus simplifies engineers to integrate devices that use CAN as the hardware communication layer. Hardware-specific low-level multi-tasking protocol, simplifying and speeding up transfers. CAN-specific hardware issues such as accept filtering and bit timing are handled by the CANopen protocol. CANopen provides communication objects (COBs) for time-sensitive systems and other hardware management tasks.
EtherCAT is a single master/slave (multiple slave) architecture. The master assigns an address to each slave, controls the baud rate of the network, and performs an initial time synchronization of all devices, which can be repeated as needed. Furthermore, the master device is the only device authorized to transmit messages. The slaves are responsible for reacting to messages, inserting their own timestamped responses, and then returning them to the master.
The CANopen network can have more than one master. However, the integrator must ensure that each device has a unique address and that all devices are set to the same bitrate. The highest recommended bitrate of the CANopen system is 1000 kbps.
“EtherCAT” Application
+ Industrial automation
+ Network Protocol PLC
+ Servo motor control
+ Data collection system
+ Motion control and machine control
+ Robots
+ Material and baggage handling systems
+ Weighing system
+ Printer
+ Semiconductor production
+ Metal and pulp & paper production
+ Electric Factory
+ Wind turbines
+ Agricultural machinery
+ Milling machine
+ Tunnel control system
+ Security system
So plctop.com has learned about EtherCAT with you, if you have any questions, please comment below the article. Thanks
