EC-EAP Stack: System-wide communication with the EtherCAT Automation Protocol (EAP)

Achitecture

The EC-EAP Stack requires just a conventional Ethernet interface for the communication. In conjunction with the high performance EC-Master Link Layers, a lot of variables could be transferred at a low system load.

Cyclic Process Data Exchange

The cyclic data exchange is based on the “pushed” or “polled” principle. In “pushed” mode, each communication device (publisher) sends its data cyclically or in a multiple of its own cycle. The receiver (subscriber) can be configured to specify which data should be received from which sender. As usual with EtherCAT, the sender and recipient data are configured via an object directory and process data mapping.

Configuration

In the engineering environment of the Beckhoff TwinCAT system, the EtherCAT Automation Protocol is configured as an I/O device. With the EAP configurator the communication between all EAP devices could be defined, e.g. editing variables and setting update rates. For each EAP device the result is stored in a corresponding EAP Device Configuration (EDC) file. The EC-EAP stack initialize all internal variables, object and frames by evaluating this EDC file and is able to start communicating afterwards.