Chapter 7: Computer Link Function
[8]Cyclic transfer and data area
(1)Outline of the cyclic transfer process
The cyclic transfer process is a function that supports cyclic data exchanges that occur between nodes.
1 Establishes the common memory function.
2 Transmits when a node receives the token.
3 Nodes which do not execute cyclic transfers within the network are allowed to participate.
4 When received the token, the node sends all the cyclic data that it needs to send.
-Token: Generally, only one token exists in a network. If more than one token exists in a network, the token with the lowest destination node number has priority and any other token is discarded.
-Token frame: A frame with a token has a destination node number and a transmitting node number. The node whose number matches the destination node number holding the token.
-Token order: The token rotation order is determined by the node numbers. The token is passed to the nodes in order that the nodes were registered in the participating node man- agement table. The node with the highest node number hands the token over to the node with the lowest node number.
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Time | Node #1 Node #2 Node #3 | Node #N |
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| Token |
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Node #1 Node #2 Node #3 | Node #N |
Token |
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Token rotation and cyclic transfer 1
Time | Node #1 Node #2 | Node |
Token
Node #1 Node #2 | Node |
Token
Token rotation and cyclic transfer 2