Understanding EtherCAT

EtherCAT is, in a sense, a synergy of several distinct technologies and developmental efforts, starting with the "fieldbus."

"Fieldbus" is a broad, non-specific term which describes an updated digital communications system in an industrial setting. An industrial system that makes extensive use of automation - for example, a modern automobile assembly line which uses robots for assembly, welding, painting and other repetitive tasks - requires a highly organized, multi-level structure of controllers to function efficiently.

This usually requires a top-level unit called a Human Machine Interface where a human operator monitors and controls the system; followed by a middle-level comprised by a number of Programmable Logic Controllers (PLCs) which are linkedto the upper-level HMIs by a communications system; and finally, the "fieldbus" which links the PLCs to the actual operational components such as motors, actuators, sensors, etc.

In a human organization, one can think of the HMI as the top-level manager (or Chief Operating Officer) who oversees and directs the company's operations; the PLC is the equivalent of the company's 'middle managers' who head up separate divisions dealing with specific areas of company operations; and the 'operators' - or the people working under the middle managers who handle specific, day-to-day operations or activities: field agents, mechanics, drivers, support personnel, etc.

The 'fieldbus' is the communications system which links the field personnel to the middle managers, providing status reports, implementation data, etc. which are processed and forwarded to the COO.

Although the communication linkages between the different levels may appear to be simple, this can become increasingly complex if one considers the multitude of actions and activities that take place at the 'field' level - many of which have to be coordinated with each other, requiring an exchange of information at that level and going upwards to 'middle managers' which, in turn, have to interact and communicate with each other, and so on.



Posted by: Wasim Javed