Description

EtherCAT is a real-time Ethernet protocol using standard Ethernet frames. An EtherCAT network typically includes one EtherCAT MainDevice and one or more EtherCAT SubDevices. The MainDevice sends Ethernet frames to the network, while SubDevices process frames and extract or insert data "on the fly".

Configuration

The EtherCAT SubDevice firmware provides a mailbox interface for configuration and supports configuration via packets or a database (config.nxd). An EtherCAT MainDevice reads the vendor ID, product code, and revision number of a SubDevice. These three parameters, among others, must be supplied to the firmware. An EtherCAT SubDevice Information (ESI) file, which describes the SubDevice, must be provided. Typically, a complex EtherCAT SubDevice includes a SubDevice Information Interface (SII) and an object dictionary (OD). Access to the OD uses the CAN application protocol over EtherCAT (CoE). The SII and OD can be created and initialized during configuration when using the "application controlled" startup.

Cyclic Data Exchange

EtherCAT uses a cyclic process data image. Each MainDevice or SubDevice in an EtherCAT network has an input and output data image, updated via cyclic Ethernet frames. Applications access the cyclic process data through the netX Host Interface (e.g., parallel DPM, serial SPM, PCIe).

Acyclic Data Exchange

The EtherCAT mailbox enables acyclic data exchange between an EtherCAT SubDevice and an EtherCAT MainDevice. An application can register for read and/or write indications to CoE objects. This allows the application to react when the MainDevice accesses objects in the CoE object dictionary. The process data image layout can be described by CoE objects. Applications can also register for read and/or write indications to the SII.

EtherCAT State Machine

The Hilscher EtherCAT SubDevice firmware lets user applications monitor and control state changes of the EtherCAT State Machine (ESM). For example, an application can proceed to a state only after synchronization is established. If no user interaction is needed, the firmware manages the ESM automatically.

Important Specifications

For an EtherCAT SubDevice, the following EtherCAT Technology Group (ETG) specifications apply:

• ETG.1000

• ETG.1020

• ETG.1300

• ETG.2000

• ETG.7000