EtherCAT Overview

EtherCAT® (Ethernet for Control Automation Technology) is a communication method for use between industrial devices and based on Ethernet technology. EtherCAT was developed by Beckhoff Automation in April 2003 and is currently supported by the EtherCAT Technology Group. EtherCAT provides high-speed and low-latency communication, making it well-suited for motion control.

The RMC200 ECAT module supports EtherCAT communication to drives, valves, sensors, and other I/O devices. An RMC200 equipped with an EtherCAT module is a MainDevice (master) on the EtherCAT network. EtherCAT equipped peripherals which connect to the RMC such as valves, drives, and sensors are SubDevices (slave devices).

The RMC does not support SubDevice functionality or MainDevice to MainDevice communication. Therefore, the RMC cannot be connected to an EtherCAT network controlled by another MainDevice. For example, the RMC cannot be connected to a Beckhoff EtherCAT MainDevice controller.

Important EtherCAT Concepts

• EtherCAT Topology

• ESI Files

• Process Data Object (PDO)

• Object Dictionary

• EtherCAT Input/Output Data Maps

• EtherCAT State Machine

• Init Commands

• EtherCAT Modules

• DC Synchronization

• Device Identification

Startup Procedure

The following topics provide information on starting up an RMC with EtherCAT:

• Creating a New EtherCAT Network

• Assigning EtherCAT Data to Axes

Using EtherCAT with Drives

The RMC EtherCAT supports drives conforming to CiA402 (CoE). The RMC does not support SoE. To learn how to use EtherCAT drives with the RMC:

• Using Drives with EtherCAT

• Drive Modes of Operation

Instructions for Third-Party EtherCAT Drives:

• Omron

• Parker

• Moog

• Copley

• Yaskawa

• AMC

Using EtherCAT with Valves

The RMC EtherCAT supports drives conforming to CiA408. To learn how to use EtherCAT valves with the RMC:

• Using Valves with EtherCAT

Instructions for Third-Party EtherCAT Valves:

• ATOS

• Moog

• Parker

• Rexroth

Using EtherCAT with Sensors

Instructions for Third-Party EtherCAT Sensors:

• Balluff

• Temposonics

Unsupported Features

EtherCAT includes many features and few devices support all of them. Some important features that the RMC currently does not support and are planned for a future release are:

• Service Data Objects (SDO) in user programs

  An SDO is data sent only when specifically requested, as opposed to Process Data Objects (PDO) that are continuously transferred. SDO’s are useful for occasional data and configuration data. A future release will support SDO communication via user programs.

• Sync Units

  SubDevices on a network can be grouped into different Sync Units. When one SubDevice in a Sync Unit faults, all SubDevices in that Sync Unit faults. Currently, all SubDevices must be in the same Sync Unit, so if one faults, they will all fault. A future release will support multiple Sync Units so that if one SubDevice faults, all SubDevices will not fault.

• Full Discrete I/O Support

  Discrete inputs and outputs via EtherCAT is supported today, but cannot be used in the Set/Clear/Toggle Discrete Output Commands, and cannot easily be mapped to individual bits in the RMC. A future release will streamline this.

• Combining I/O Values from Bytes

  Some SubDevices provide individual data values in separate smaller units, such as bytes that must be combined into one unit. For example, a 32-bit floating point value may be provided in four separately addressed bytes. Currently, expressions in user programs must be used to combine these. In the future, Delta plans on providing a simple method to combine these.

Notable features for which there are currently no plans of supporting:

• Hot Connect Groups

• Main Device Redundancy

• Synchronizing multiple EtherCAT networks

See Also

RMCTools Overview

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