1.2. Why does EtherCAT provide cost advantages?
1.3. Is EtherCAT limited to Master/Slave Applications?
1.4. EtherCAT specifies two different physical layers - why?
1.5. How is the interoperability of EtherCAT devices maintained?
2.2. Do I have to be an ETG member to implement EtherCAT?
2.3. What are the ETG membership benefits?
2.4. ETG Membership is free - why?
2.5. And will this be changed?
2.6. How do ETG members have an impact on the technology?
3.2. Are there any patents?
3.3. How about licenses?
3.4. Are there multiple sources for the EtherCAT Slave Controller?
3.5. Will the ASICs replace the FPGAs?
4.2. How much is the FPGA?
4.3. We want to implement an EtherCAT Slave device - what do we need?
4.4. We want to implement an EtherCAT Master device - what to we need?
Superior fieldbus performance never harms. Even with slow controls, it improves reaction times and reduces configuration effort, since default settings will do the job. Furthermore, shorter reaction times improve the performance of your application, since the transition waiting times are reduced (e.g. waiting for an input signal before the next process step is initiated). If you do not care so much about performance though, use EtherCAT for its other benefits: e.g. lower costs, more flexible topology or simply ease of use. Or, why use a slower system just before it is more expensive?
For several reasons: Inexpensive slave controllers lead to lower slave device costs. No special master card required, the on-board Ethernet controller is sufficient. No switches or hubs required, therefore lower infrastructure costs. Use of standard cabling. Simple to implement, therefore lower implementation costs. Auto-configuration is supported, no manual address setting required, no network tuning required, therefore lower configuration costs.
No. Like with every real time Industrial Ethernet system, one device (the master) has to be in charge of the network management and organize the Medium Access Control. With EtherCAT, Slave to Slave communication is supported in two ways: topology dependent within one communication cycle ("upstream" device talks to "downstream" device), topology independent within two cycles. Since EtherCAT is so much faster than competing systems, slave-to-slave communication using two cycles is faster, too.
EtherCAT uses standard 100BASE-TX ("Fast Ethernet") on standard CAT5+ cables. For applications that require longer distances, the fibre optics 100BASE-FX is an alternative. Since EtherCAT is also used as "backplane bus" for modular devices, an even lower cost physical layer from IEEE802.3ae was added for such applications: LVDS (also called: E-Bus). Outside such modular devices, the physical layer is changed back to 100BASE-TX or -FX.
Conformance and Interoperability are very important factors for the success of a communication technology. Therefore the EtherCAT Technology Group is taking these topics very seriously. The ETG organizes plug fests, where developers meet to test and improve the interoperability of their devices. A conformance test tool has been developed, and the ETG task force conformance testing is constantly enhancing the test cases for this tool. Conformance test labs are being prepared right now. Each device vendor signed the vendor-ID agreement and thus is bound by contract to maintain interoperability and prove conformance if necessary.
No. However, you may want to consider joining the ETG in order to indicate your interest in and support for this technology to your suppliers and customers. As an ETG member, you are invited to attend the ETG meetings, you get access to technology information, draft specs and can influence the direction in which the technology moves.
There are several ways to implement an EtherCAT device. If you use an interface device of a technology provider that contains the entire EtherCAT interface including the object dictionary, your technology provider may remain responsible for the conformance of the device. If you also use his vendor ID (which means that configuration tools list the product under the technology providers name), you do not necessarily have to be an ETG member, even though we would recommend this (see also 2.3). If you want your own vendor ID, or implement an EtherCAT slave controller directly, or use an interface device where you can modify the stack you are responsible for the conformance of the device. In this case you have to join the ETG and obtain a vendor ID, which is free of charge.
ETG members enjoy preferred support, get access to draft EtherCAT specs, sample code, evaluation kits and other supportive tools and information which is available for ETG members only, giving ETG members a head start while using the technology. They are invited to the ETG meetings, where the specs are reviewed and discussed. Furthermore, ETG members may promote their products on the EtherCAT website and on the joint ETG booths at major trade shows.
Access to an open technology should not be a question of annual membership fees or other significant costs. Therefore not only the ETG membership is free of charge, but for ETG members protocol stacks, sample code, evaluation kits, implementation support and other services are either free or available for a nominal fee.
There are no plans to charge for the ETG membership. If there is a need for membership fees in the future (e.g. to support additional services provided by the ETG), the membership assembly will have to take this decision.
At the ETG meetings the EtherCAT technology is presented and discussed in detail. Members are encouraged to provide comments, propose enhancements and changes at any time. This feedback and the requirements of users, OEMs, system integrators and device manufacturers are both valuable and welcome and considered for implementation. The ETG history showed that this approach works very efficiently. Direct and personal contact between technology users and developers allow for in-depth exchange of know-how and technical information.
This means that everybody may use, implement and benefit from this technology. This also means that EtherCAT implementations have to be compatible, and nobody may change the technology in a way that prevents others to use it. EtherCAT is part of several IEC Standards (IEC61158, IEC 61784, IEC 61800), of ISO 15745, and is also a SEMI standard (E54.20).
Yes, there are patents on the EtherCAT technology just like there are patents on every other fieldbus technology that is worth it. Technologies that provide unique features need patents and licences to protect them from being copied or falsified.
The license for implementing an EtherCAT master is free of charge. For slave devices EtherCAT has adopted the CAN license model (CAN is an excellent example for a standardized open technology that is protected by patents): The small license fee is "embedded" in the Slave Controller Chip, so that device manufacturers, end users, system integrators, tool manufacturers etc. do not have to pay a license.
Yes. EtherCAT Slave Controller implementations are available from Beckhoff, Hilscher (netX), as well as from Altera and Xilinx (FPGAs). Further implementations will follow.
When you purchase your FPGA from your preferred semiconductor distributor, the EtherCAT code is not already loaded. EtherCAT IP-core licenses are available both for Altera and Xilinx FPGAs. There are licenses available that entitle you to manufacture as many EtherCAT slave devices as you want. Alternatively, there are quantity based licenses available, too.
The IP-Cores provide freely configurable EtherCAT functionality, so that you can adapt the core-size to your requirements. You can also add application specific functions to the same FPGA, including soft-core processors. This further lowers the hardware costs for the EtherCAT slave device.
ETG member companies are entitled to purchase FPGAs for a special price, which leads to lower costs for an EtherCAT interface than most legacy fieldbus interfaces.
A good starting point is the slave implementation guideline, available for download here.
EtherCAT Slave Implementation kits are available from several suppliers. One kit, for example, contains a slave device evaluation board with EtherCAT slave controller, the slave protocol stack in source code (optional for simple devices), reference hardware design information, evaluation license for EtherCAT master, manuals and cables.
For a master device, you do not need a special hardware. Any Ethernet MAC will do. Since EtherCAT is very easy on resources, you do not need a dedicated communication processor, either. Master code is available from several suppliers, ranging from several free of charge open source projects via a sample code package to products that include the RTOS. Implementation services are also available from several suppliers. Please check out the product guide here.