Method for transmitting messages in a communication network
A method is disclosed for transmitting messages in a communications network with at least three communications nodes. At least one communications node always remains active and stores messages sent by a second communications node. If the second communications node switches to an idle state, the caching node is informed thereof by means of a sleep-event and takes over the sending of the messages for this node. By means of a wake-up event, the caching node obtains information that the second node has switched back into the active state and ceases sending the stored messages. Further nodes, which likewise can switch to the idle state at any time and possibly not receive messages sent by the second node during their own idle phase, thus do not notice anything about the idle state of the second node and operate on the assumption of an up-to-date status in the network at all times.
1. A method for transmitting messages in a communication network having at least communication nodes, comprising:
maintaining at least one of the communication nodes always in an active state;
transforming at least one of the communication nodes from the active state to a quiescent state while it is not required for communication;
informing, an active communication node, of a change in a particular communication node from the active state to the quiescent state by a sleep event and of a change in the particular communication node from the quiescent state back to the active state by a wakeup event;
storing messages or copies of messages from the particular communication node in an internal data memory of the active communication node;
the active communication node sends the stored messages or copies of messages in response to being informed of a change in the particular communication node from the active state to the quiescent state;
the active communication node transmitting, from the internal data memory to an internal hardware data memory, messages or copies of messages to be sent, and the active communication node stops sending the stored messages or copies of messages and erasing from the hardware memory or copies of messages to be sent in response to being informed of a change in the particular communication node form the quiescent state back to the active state.
2. The method of claim 1 , wherein the communication network is a vehicle bus.
3. The method of 1 , wherein the active communication node is a controller or a gateway.
4. The method of claim 1 , wherein at least one of the sleep event and the wakeup event is a network management message including information that indicates the status of the node whose messages are stored by the active node.
5. The method of claim 1 , wherein at least one of the sleep event and the wakeup event comprises any piece of information suitable for identifying the state change in a node.
6. The method of claim 5 , wherein the sleep event and/or the wakeup event is an information flow that is effected by measurable changes in the environment.
7. The method of claim 1 , wherein individual messages are excluded from storage in the constantly active communication node.
8. The method of claim 1 , wherein the copy is a copy of individual contents of the message.
9. The method of claim 1 , wherein a copy of a message sent by the active node has a different ID than the original message.
10. The method of claim 1 , wherein the sending of a stored message by a communication node is a wakeup event.
11. The method of claim 1 , wherein a message and the copy thereof are never sent in a communication network simultaneously.
12. The method of claim 1 , wherein a communication node does not send further messages for a particular period after it has sent a wakeup event.
13. The method of claim 12 , wherein the active communication node stops sending messages stored after the particular period.
14. The method of claim 1 , wherein a communication node is re-enabled to send messages after a wakeup event has been sent.
15. The method of claim 14 , wherein the active communication node sends no further stored messages from the relevant communication node directly after a wakeup event has been received.
16. The method of claim 15 , wherein the active communication node removes the messages from the hardware data memory immediately after the wakeup event has been received.
17. A network having at least three communication nodes that is used for transmitting messages,
wherein at least one of the communication nodes is always kept in an active state,
wherein at least one of the communication nodes is changed from the active state to a quiescent state while it is not required for communication,
the active communication node is informed of a change in a particular communication node from the active state to the quiescent state by a sleep event and of a change in the particular communication node from the quiescent state back to the active state by a wakeup event,
the active communication node has an internal data memory that stores messages or copies of messages from the particular communication node, and sends of these messages or copies of messages in response to being informed of a change in the pa particular communication node from the active state to the quiescent state,
wherein the active communication node has a hardware data memory to which it transmits messages or copies of messages to be ready for sending and that are stored in the internal data memory of the active communication node, and
wherein the active communication node stops sending the stored messages or copies of messages from the particular communication node and erases the messages or copies of messages ready for sending in the hardware data memory in response to being informed of a change in the particular communication node from the quiescent state back to the active state.