The EtherCAT has become the most widelyadopted fieldbus for implementing motion control in a machine automation and real-time control system. There are several fieldbus standardsthat are very similar in terms of performanceand fundamental characteristics including EtherCAT, Profinet IRT and Sercos. At first glance, all the architecture delivers the core functionality required by a fieldbus:
- Determinism: determinism is the ability to offer repetitive and precise timing as required to consistently control processes. This includes the ability to service an EtherCAT network in a timely manner.
- Standard Ethernet interfaces are inexpensive, so these fieldbuses have created a new protocol that can reuse the TCP cable and NIC card rather than relying on expensive proprietary cabling.
- Finally, these protocols can be plugged into controller that runs on an Industrial PC. One of the important reasons for applying PC based control systems is to pave way for the co-existence of Windows applications. For example, vision processing systems, HMIs, data processing and gathering applications provide the ability to interact with high level IT systems.Running on a PC also paves the way for a future where the Machine Controller becomes part of the IoT and Industry 4.0 solution.
A clean interface can be effectively established between a real-time platform and Windows platform by implementing a comprehensive control library that is linked to C++, C# or a VB.Net program. Such a library communicates with the fieldbus master controller that operates under a Real-time operating system. It can further bridge the communication gap in a controlled manner without impacting system performance.
So at a highlevel, the fieldbuses look comparable but drilling down into the architecture it becomes clear very quickly that EtherCAT offers the simplest architecture with the least cost. So it is no surprise that most automation drive vendors have embraced EtherCAT whereas only a handful of drive vendors embrace Profinet IRT or Sercos. If you are to adopt a standard, there it is good to adopt the standard that is best supported. The reason that people might adopt Profinet or Sercos is that while there are fewer drive vendors that offer the solution, those vendors will sell you all the hardware from PLC, to Drive, to motor and so on. The downside is that there is a premium to be paid for not being able to swap out components.
EtherCAT is designed to address the need for a rapid cyclical update of devices with low jitter rates required by modern day fieldbuses. This is essential for motion control and real-time platform applications. This is because, EtherCAT is a beneficial fieldbus that can utilize standard Ethernet cabling with a few limitations. And it is the most widely supported standard by the drive vendors that sell into industrial automation.