EMCY write protocol

The EMCY write protocol is triggered by the occurrence of a CANopen FD device internal error situation and is transmitted from an emergency producer on the CANopen FD device. EMCYs are suitable for interrupt type error alerts. An EMCY is transmitted only once per error event. No further EMCYs are transmitted as long as either no new error occurs or is removed on a CANopen FD device.

As the EMCY write protocol is communicated in broadcast, any CANopen FD device that supports the EMCY consumer functionality can receive the EMCY write protocol and adjust its behavior according to the reported error event. The fault reaction on the EMCY write protocol consumer is manufacturer-specific.

EMCY write protocol

By means of the EMCY write protocol the producer reports on the occurred, application-specific error event. The communicated error information corresponds to one entry in the active error history (data object 1031h) and covers:

  • Error register
    (type of error (see data object 1001h))
  • Emergency error code (EEC)
    (detailed error information, supplementing the type of error indication)
  • Device specific error information
    (additional manufacturer-specific error information)
  • CiA specification number
    (CiA specification that defines aforementioned EEC)
  • Logical device number
    (part of the CANopen FD device, where the error occurred)
  • Status
    (type of error; e.g. non-recoverable)
  • Time
    (time information; when did the error occur)