Yaskawa JAPMC-MC2303-E - Manual (Page 157)

Appendix B FL-net Network Management
B.1 FL-net Token Management
A-7
App
Appendices
Appendix B FL-net Network Management
B.1 FL-net Token Management
( 1 ) Token
Basically, the node is not allowed to send data unless it has a token.
However, it is allowed to send data in the following cases even if it does not hold the token.
• When a token is issued again because it has disappeared
• When a join request frame is sent for a node to join the network
The following gives a brief description of token function.
• In FL-net, one token is passed among nodes joined to the network.
• Each node holds rights to send data to the network from when it receives a token until it passes the token to the
next node.
• The token is monitored by the timer of each node. If a token is not circulated in a specified period of time, it is
reissued automatically.
• When two tokens are circulating on a network, one is deleted to allow only one token to be circulated on the net-
work.
( 2 ) Token Flow
Basically, only one token is present in the network.
When two or more tokens are present in the network, the node selects the token with a smaller node number and dis-
cards the other.
A frame holding a token (called a token frame) has a token destination node number and a token passing node number.
Each node serves as a token holding node only when it has a token number identical to the token destination node num-
ber of a received token frame.
The token rotation sequence depends on node numbers.
Each node passes the token in the ascending order of node numbers registered in the joined node management tables of
each node.
A node having the maximum node number passes the token to a node having the minimum node number.
MP2200 218IF-02 262IF-01 LIO-04 SVB-01 CPU-02 LIO-04 LIO-04 LIO-01 LIO-01
MP2200 218IF-02 262IF-01 LIO-04 SVB-01 CPU-02 LIO-04 LIO-04 LIO-01 LIO-01
MP2200 218IF-02 262IF-01 LIO-04 SVB-01 CPU-02 LIO-04 LIO-04 LIO-01 LIO-01
MP2200 218IF-02 262IF-01 LIO-04 SVB-01 CPU-02 LIO-04 LIO-04 LIO-01 LIO-01
Passes to a node having the minimum
node number.
Node 2 Node 3 Node N-1
Node 1 Node N
Passes token to the next node.