ProSoft Technology MVI69-FLN - Manual (Page 78)

MVI69-FLN ♦ CompactLogix Platform Reference
FA Control Network Communication Module
Page 78 of 137 ProSoft Technology, Inc.
November 3, 2008
3 Dual communications functions to suit application
The Common Memory function uses cyclic transmission so that each node
can always share the same data with other nodes on the network. FL-net also
supports message communications for use when handling only essential data
is required.
4 Large-capacity Common Memory
The Common Memory is provided with a large capacity of 8K bits (Area 1)
and 8K words (Area 2).
5 High-speed response
High-speed response time of 50 milliseconds / 32 nodes (for 2K bits and 2K
words) is provided. The absence of a master in the FL-net network enables
nodes to be added or removed readily without affecting any other nodes. This
allows any node to be turned ON or OFF easily and facilitates maintenance.
The FL-net protocol is characterized by the following items:
1 Transmission control using masterless token system avoids collision.
2 Refresh cycle time can be specified since the system circulates a token in a
fixed time.
3 The token is transmitted together with a cyclic data.
4 The node with a smallest node number among those who participate the
network at start-up time shall start to send the token.
5 If no token is transmitted for a specified period, next node in the token
circulation ring shall send a new token.
6 The masterless token system (characterized by the above two items) will
keep the network from stopping in case of failure of some nodes.
7 The protocol provides information management tables for useful information
to refer operation status of other nodes such as operation mode (RUN /
STOP) and hardware malfunction (ALARM).
Data Communication Between Nodes
Types of Data Communication
The FL-net protocol supports 2 types of data communication.
1 Cyclic transmission for cyclic data transmission
2 Message transmission for non-cyclic data transmission
Cyclic transmission
The common memory size is 8k bits + 8k words = 8.5k words in a whole network.
Available amount of transmission data in one node is 8.5k words at maximum.
One word consists of 2 bytes.
Message transmission
Maximum data length of one message frame is 1024 bytes (excluding header).