Error Control; Heartbeat Mechanism; Node Guarding1; Emergency Object (Emcy) - HMS Anybus X-gateway CANopen Series User Manual

6.4 Error Control

Different mechanisms exist to monitor the network. At an error event from any of these, the active I/O
data is frozen, as no new data will be available.

6.4.1 Heartbeat Mechanism

The Heartbeat Mechanism is used to monitor the nodes in the network and verify that the nodes are
available. A heartbeat producer periodically sends a message. The data part of the frame contains a byte
indicating the node status. The heartbeat consumer reads these messages. If a message fails to arrive
within a certain time limit (defined in the object directory of the devices, objects 1016h and 1017h, 31),
a heartbeat event is registered by the consumer. The ERROR LED on the front of the Anybus X-gate-
way CANopen and the status word will indicate the event. An EMCY object (8130h) is also transmitted
on the CANopen fieldbus. If the module is configured as a slave and is in OPERATIONAL state, it will
go to PRE-OPERATIONAL state and wait for the user to take action. If it is in master mode, it will
take action according to the settings in the master objects.
The Anybus X-gateway CANopen can act both as heartbeat consumer and as heartbeat producer.
6.4.2 Node Guarding
The NMT Master transmits guarding requests. If an NMT Slave has not responded within a defined time
span (node lifetime) or if the communication status of the slave has changed, the master takes appropri-
ate action according to its configuration.
If Life guarding (the slave guards the master) is supported, the slave uses the guard time and lifetime
factor from its Object Dictionary to determine the node lifetime. If the slave does not receive a guarding
request within its lifetime, a node guard event is registered. The ERROR LED on the front of the
Anybus X-gateway CANopen will indicate the event. An EMCY object (8130h) is also transmitted on
the CANopen fieldbus.
If the guard time or the lifetime facter are 0 (default), the Slave does not guard the Master. The guarding
can be initiated at boot-up or later.
Note: If heartbeat is enabled, node guarding is disabled.

6.4.3 Emergency Object (EMCY)

The Emergency Object is used for error reporting on the CANopen network when a fatal fault has oc-
curred. The error codes are saved in a list in the Communication Profile Object 1003h, see 30 and a mes-
sage is produced on the CANopen network. A list of emergency error codes, that can be produced by
the module, is available in "CANopen Emergency Codes" on page 46
1. The NMT master can monitor a slave either by heartbeat or by node guarding. Only one of these mechanisms at the time can be
active. Heartbeat is preferred and if heartbeat is enabled in a slave, any node guarding for that slave is disabled.
Anybus X-gateway CANopen - PROFIBUS
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CANopen Module Specification 29
Doc.Id. SCM-1200-080