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EtherCAT servo drives

EtherCAT ports

EtherCAT connections follow the standard Ethercat topologies:

  • Port 0: IN (input) port, which has to be connected always.
  • Port 1: OUT (output) port, which has to be connected to more EtherCAT slaves in the network and/or for closed ring topologies.

EMCY service

The EMCY service is an asynchronous producer-consumer protocol on which the producer indicates that an error has been detected by sending an EMCY message. The consumer can easily know the error source that has been detected by the node at the error instant without polling the statusword or the error register. 

Each produced EMCY message is reflected in register 0x1001. The EMCY message can both indicate that an error has been produced and also that an error condition has been removed (error code "no error"). Each error indicates the code of the error, and also the affected module. 

An emergency object is sent only once per error event.

The data content of the emergency message uses the following structure:

Byte number:










Emergency error code

Error register
(Object 0x1001)


Reserved (zero values)

Example of EMCY

Event (Twincat captures)Description
Drive reports an emergency message indicating an user under-voltage detected (0x3241) in the subnode 1. Register 0x1001 = 5 indicates the active error with its corresponding bits 0 and 2 set to 1.

Drive indicates that the error condition in the subnode 1 has been removed (errorcode = 0x0000). Register 0x1001 = 0 indicates that there are no other active errors at this moment.

This EMCY message has been sent in the fault reset event.

Refer to the Error management section for the error code description list.

Everest products only

Linking faults with EMCY service (Everest products only)

Faults can be linked to EMCY service by means of register error notification source. Further information can be found in Error management section.

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