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5.3.1.3.1 SYNC Protocol

5.3.1.4 Emergency Object (EMCY)

Emergency objects are triggered by an internal error situation such as i.e. a module is removed during operation, or a module signals an error. The bus coupler then sends an emergency object to all connected devices (Broadcast), to broadcast the error occurred. The informed bus subscribers can then react accordingly by suitable error correction measures.

5.3.1.4.1 EMCY Protocol

More Information

A detailed description to the Emergency messages, please refer to chapter 5.3.9 "Error Message (Emergency)".

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5.3.2 Communication states of a CANopen fieldbus coupler/controller

5.3.2.1 CANopen state diagram

The status diagram described in the following figure shows the individual communication states and possible transitions related to the CAN communication.

5.3.2.2 INITIALIZATION

Following a power On or a reset (module ID unequal 0), the bus coupler is automatically in the INITIALIZATION status. In this status, the bus coupler performs a self-check to check all functions of its components and the communication interface. The process image is created on the basis of the connected modules and a possibly stored configuration, and the object directory initialized. If no errors are detected during the initialization phase the bus coupler automatically changes to the pre-operational status. If errors were found, a change to the STOP status takes place.

During initialization, the I/O-LED starts blinking orange and changes to red at its higher frequency. If initialization and the change to the pre-operational status have been successfully completed, the I/O LED is lit green and the RUN LED blinks. If errors have occurred (i.e. no end module connected) the I/O LED indicates the error type by a red blinking sequence (see LED status display). In this case, the STOP LED is lit red.

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5.3.2.3 PRE-OPERATIONAL

In this status, communication can be made via SDOs. Communication via PDOs is not possible. The SDOs allow for reading and writing in the entries of the object directories permitting for instance to re-configure the bus coupler by means of the configuration tool. Mapping, bus coupler parameters, IDs etc. can in this manner be adapted to the required conditions. The newly configured configuration can be saved in flash.

A change from the pre-operational status to the operational status is performed by means of the NMT service Start_Remote_Node.

In the pre-operational status the I/O LED is lit green and the RUN LED blinks.

5.3.2.4 OPERATIONAL

This status allows communication via SDOs and PDOs, it does, however, not allow different configurations. It is, for instance, not allowed to change the COB ID in the presence of a valid PDO. For a detailed description, please refer to the corresponding entries in the object directory.

The change from the operational status to the pre-operational status is performed with the NMT service Enter_Pre_Operational_State.

In the operational status, the I/O and the RUN LED are lit.

5.3.2.5 STOPPED

The Stopped status reflects an error status. This is the case if the NMT service Stop_Remote_Node was received or if a fatal internal error has occurred (i.e. module was removed during operation).

This status does not allow communication via SDOs or PDOs. Only the NMT services and the Node Guarding/Heartbeat (if activated) are performed.

You can quit the Stopped status via the NMT services Start_Remote_Node_Indication, Enter_Pre_Operational_State and Reset_Node.

The Stop LED is lit in the Stopped status.

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CANopen